不就是個blog

Lambdas in Java Preview - Part 1: The Basics

Lambdas in Java Preview - Part 2: Functional Java

Lambdas in Java Preview - Part 3: Collections API

Lambdas in Java Preview - Part 4: Proposal Update

Lambdas in Java Preview - Part 5: Apache Wicket

經歷ASP、PHP、JSP、Tapestry、Wicket、Rails，目前正在使用的是Play framework。開發時只需用內建的server，修改java程式或HTML網頁之後，只要refresh就能看到結果，Play會幫我們編譯java檔。部署時可以用內建的server，也能打包成war檔放進application server，若要部署至Google App Engine也有GAE module可用。Play也把Hibernate包裝好了，使用時不再需要繁瑣的設定。其它如MongoDB、Scala、Spring、GWT等也已經有支援模組。就像Rails，Play也有內建routes功能可以讓你輕鬆開發RESTFul application，或是讓URL看起來漂亮些。

A web app in 10 minutes using Play! from zenexity on Vimeo.

• maxConnectionsPerPartition最小值是2，給了小於2的值會被設成50
• minConnectionsPerPartition最小值是2，給了小於2的值會被設成10
• minConnectionsPerPartition大於maxConnectionsPerPartition時，會被設成maxConnectionsPerPartition
• acquireIncrement小於或等於0時，會被設成1
• partitionCount小於1時，會被設成3
• releaseHelperThreads小於0時，會被設成3
• statementsCacheSize小於0時，會被設成0
• acquireRetryDelay小於或等於0 時，會被設成1000

有時候要把Maven調教成想要的樣子真的很麻煩，自己刻Ant build file比較快，但是這樣就要自己管理dependencies，引用很多library的時候會很痛苦，還好有Ant Tasks for Maven可以幫忙減輕痛苦。下載maven-ant-tasks-*.jar後扔進$APACHE_HOME/lib目錄就可以用了。

使用時可以像用Maven時一樣，把dependencies資訊存入pom.xml，再從build.xml引用。

pom.xml:

<?xml version="1.0" encoding="UTF-8"?>
<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>net.zbwei</groupId>
  <artifactId>bento</artifactId>
  <packaging>war</packaging>
  <name>bento</name>
  <version>0.1</version>
  <dependencies>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring</artifactId>
      <version>2.5.5</version>
    </dependency>
    <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate</artifactId>
      <version>3.3.0.ga</version>
    </dependency>
  </dependencies>
</project>

build.xml:

@Entity
@Table(name="memberships")
@IdClass(MembershipPK.class)
public class Membership {
        private Integer groupId;

        private Integer userId;

        @Id
        @Column(name="group_id")
        public Integer getGroupId() {
                return groupId;
        }

        public void setGroupId(Integer groupId) {
                this.groupId = groupId;
        }

        @Id
        @Column(name="user_id")
        public Integer getUserId() {
                return userId;
        }

        public void setUserId(Integer userId) {
                this.userId = userId;
        }
}

@Embeddable
public class MembershipPK {
        private Integer groupId;

        private Integer userId;

        public Integer getGroupId() {
                return groupId;
        }

        public void setGroupId(Integer groupId) {
                this.groupId = groupId;
        }
        
        public Integer getUserId() {
                return userId;
        }
        
        public void setUserId(Integer userId) {
                this.userId = userId;
        }
}

在Wicket程式用Spring，要在web.xml加入設定：

<context -param>
  <param -name>contextConfigLocation</param>
  <param -value>/WEB-INF/spring*.xml</param>
</context>

<listener>
  <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

在WebApplication中要建立SpringComponentInjector：

public class BasicApplication extends WebApplication {
  @Override
  protected void init() {
    super.init();
    addComponentInstantiationListener(new SpringComponentInjector(this));
  }
}

如果還想把bean注入WebSession，要用InjectorHolder:

public class BasicSession extends WebSession {
  public BasicSession(Request request) {
    super(request);
    InjectorHolder.getInjector().inject(this);
  }
}

設定好之後，只要在需要注入bean的地方用@SpringBean即可，範例如下：

public class SignUpPage extends BasePage {
  @SpringBean
  private UserService userService;

  public SignUpPage() {
    add(new SignUpForm("signUpForm"));
  }

  class SignUpForm extends Form {
    private String name;

    private String email;

    private String password;

    @SuppressWarnings("unused")
    private String confirmPassword;

    public SignUpForm(String id) {
      super(id);
      PasswordTextField passwordField, confirmPasswordField;
      add(new TextField("name",  new PropertyModel(this, "name")).setRequired(true).add(new StringValidator.LengthBetweenValidator(2, 32)));
      add(new TextField("email", new PropertyModel(this, "email")).setRequired(true).add(EmailAddressValidator.getInstance()));
      add(passwordField        = new PasswordTextField("password",        new PropertyModel(this, "password")));
      add(confirmPasswordField = new PasswordTextField("confirmPassword", new PropertyModel(this, "confirmPassword")));
      add(new EqualPasswordInputValidator(passwordField, confirmPasswordField));
    }

    @Override
    protected void onSubmit() {
      User user = new User(name, email, password, User.ROLE_USER);
      try {
        userService.createUser(user);
        setResponsePage(HomePage.class);
      } catch (DuplicatedUserNameException e) {
        error(getLocalizer().getString(getId() + ".nameTaken", getWebPage(), "User's name is taken: " + name));
      } catch (DuplicatedUserEmailException e) {
        error(getLocalizer().getString(getId() + ".emailTaken", getWebPage(), "User's email is taken: " + email));
      }
    }
  }
}

應用程式內嵌Jetty運行webapp時，希望程式和webapp共用同一個spring context，在web.xml設定context loader listener時，要改用自定的MyContextLoaderListener。

JettyServer.java:

import org.mortbay.jetty.Server;
import org.mortbay.jetty.nio.SelectChannelConnector;
import org.mortbay.jetty.webapp.WebAppContext;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

public class JettyServer implements ApplicationContextAware {
  private ApplicationContext applicationContext;

  public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
     this.applicationContext = applicationContext;
  }

  public void start() throws Exception {
     int port = Integer.parseInt(System.getProperty("jetty.port", "8080"));

    SelectChannelConnector connector = new SelectChannelConnector();
     connector.setPort(port);

    Server server = new Server();
     server.addConnector(connector);

    WebAppContext context = new WebAppContext();
     context.setClassLoader(applicationContext.getClassLoader());
     context.setAttribute("applicationContext", applicationContext);
     context.setServer(server);
     context.setContextPath("/");
     context.setWar("src/main/webapp");

    server.addHandler(context);
     server.start();
  }
}

MyContextLoader.java:

import javax.servlet.ServletContext;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.web.context.ContextLoader;

public class MyContextLoader extends ContextLoader {
  @Override
  protected ApplicationContext loadParentContext(ServletContext servletContext) throws BeansException {
     return (ApplicationContext)servletContext.getAttribute("applicationContext");
  }
}

MyContextLoaderListener.java:

import org.springframework.web.context.ContextLoader;
import org.springframework.web.context.ContextLoaderListener;

public class MyContextLoaderListener extends ContextLoaderListener {
  @Override
  protected ContextLoader createContextLoader() {
     return new MyContextLoader();
  }
}

Maven repository沒有Terracotta和Terracotta Maven Plugin，所以要在pom.xml加入：

  <repositories>
    <repository>
      <releases>
        <enabled>true</enabled>
      </releases>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
      <id>terracotta-repository</id>
      <url>
        http://www.terracotta.org/download/reflector/maven2
      </url>
    </repository>
  </repositories>

  <pluginrepositories>
    <pluginrepository>
      <id>terracotta-snapshots</id>
      <url>
        http://www.terracotta.org/download/reflector/maven2
      </url>
      <releases>
        <enabled>true</enabled>
      </releases>
      <snapshots>
        <enabled>true</enabled>
      </snapshots>
    </pluginrepository>
  </pluginrepositories>

  <build>
    <plugins>
      <plugin>
        <groupid>org.terracotta.maven.plugins</groupid>
        <artifactid>tc-maven-plugin</artifactid>
        <version>1.0.3</version>

        <configuration>
          
          
          
          

          
          
          
          
          
          
        </configuration>
      </plugin>
    </plugins>
  </build>

  <dependencies>
    <dependency>
      <groupid>org.terracotta</groupid>
      <artifactid>terracotta</artifactid>
      <version>2.5.1</version>
    </dependency>
  </dependencies>

不過，Terracotta DSO Eclipse Plug-in比Terracotta Maven Plugin好用多了。

RubyHelp.java:

public class RubyHelper {
  static {
    System.setProperty("jruby.home", new File("").getAbsolutePath());
  }

  private RubyHelper() {
  }

  public static Object create(String className, Class interfaceClazz, String scriptFileName) {
    InputStream scriptInputStream = Thread.currentThread().getContextClassLoader().getResourceAsStream(scriptFileName);
    if (null == scriptInputStream) {
      throw new RuntimeException("Could not find " + scriptFileName);
    }
    StringBuilder sb = new StringBuilder();
    byte[] buf = new byte[8192];
    try {
      for (int n; (n = scriptInputStream.read(buf)) != -1;) {
        sb.append(new String(buf, 0, n, "UTF-8"));
      }
      scriptInputStream.close();
    } catch (IOException e) {
      throw new RuntimeException("Error loading " + scriptFileName + ": " + e.getMessage());
    }
    Ruby runtime = JavaEmbedUtils.initialize(new ArrayList());
    runtime.eval(runtime.parse(sb.toString(), scriptFileName, runtime.getCurrentContext().getCurrentScope(), 0, false));
    return JavaEmbedUtils.rubyToJava(runtime, runtime.evalScriptlet(className + ".new"), interfaceClazz);
  }
}

HelloService.java:

public interface HelloService {
  void hello();
}

hello.rb:

class Hello
  def hello
    puts 'hello there'
  end
end

Test.java:

public class Test {
  public static void main(String[] args) throws Exception {
    HelloService s = (HelloService)RubyHelper.create("Hello", HelloService.class, "hello.rb");
    s.hello();
  }
}

• Apache MINA
• dom4j
• ehcache
• FreeMarker
• Hibernate
• Hibernate Annotations
• ini4j
• JavaMail
• Java Service Wrapper
• Jakarta Commons Logging
• JCIFS
• Jetty
• JGoodies Binding
• JGoodies Forms
• JGoodies Looks
• JGoodies Validation
• Jpcap
• jTDS
• log4j
• Proxool
• Quartz
• Spring Framework
• Wicket
• XStream
• YourKit Java Profiler

下列是DatabaseOperation提供的功能，如果有用IDENTITY欄位，要改用InsertIdentityOperation提供的INSERT、CLEAN_INSERT、REFRESH。

Wicket開發指南，作者是王磊，這本三百多頁的開發指南，應該是目前對Wicket解說最詳細的中文手冊。我用過的Java web framework只有兩個，Tapestry是第一個，第二個就是Wicket。Tapestry已經被我停用了，位子則由Wicket和Ruby on Rails一同接下。第一次知道Wicket這東西，是在Tapestry作者的blog中瞧見的。在IDE如Eclipse的 協助下，熟悉Java的程序員使用Wicket的開發速度可以非常快，雖然在persistence layer要用JDBC或Hibernate，不如Ruby on Rails的ActiveRecord省事，但在presentation layer的用法則是我所喜愛的，這也是早期採用Tapestry的原因，Rails中調用簡便的AJAX，在Wicket也有良好支援。至於 Struts和Spring MVC，雖然沒事偶爾會看看，但是，看看就好，完全不想用(真是任性啊！)。目前要我開發web app的話，不是Wicket，就是Ruby on Rails了。

<?xml version=”1.0″ encoding=”UTF-8″?>
<!DOCTYPE beans PUBLIC
  “-//SPRING/DTD BEAN/EN”
  “http://www.springframework.org/dtd/spring-beans.dtd”>

<beans>
  <bean id=”dataSource” class=”org.logicalcobwebs.proxool.ProxoolDataSource” destroy-method=”close”>
  <property name=”driver”><value>${jdbc.driver}</value></property>
  <property name=”driverUrl”><value>${jdbc.url}</value></property>
  <property name=”user”><value>${jdbc.username}</value></property>
  <property name=”password”><value>${jdbc.password}</value></property>
  <property name=”alias”><value>xfort</value></property>
  <property name=”houseKeepingTestSql”><value>SELECT 1</value></property>
  <property name=”testBeforeUse”><value>false</value></property>
  <property name=”maximumActiveTime”><value>86400000</value></property>
  <property name=”maximumConnectionCount”><value>${proxool.maximum-connection-count}</value></property>
  <property name=”delegateProperties”><value>user=${jdbc.username},password=${jdbc.password}</value></property>
</bean>

<bean id=”sessionFactory” class=”org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean”>
  <property name=”dataSource”><ref bean=”dataSource” /></property>
  <property name=”hibernateProperties”>
    <props>
      <prop key=”hibernate.dialect”>${hibernate.dialect}</prop>
      <prop key=”hibernate.format_sql”>true</prop>
      <prop key=”hibernate.show_sql”>false</prop>
      <prop key=”hibernate.cache.use_second_level_cache”>false</prop>
      <prop key=”hibernate.cache.provider_class”>org.hibernate.cache.EhCacheProvider</prop>
      <prop key=”hibernate.current_session_context_class”>thread</prop>
      <prop key=”hibernate.connection.release_mode”>after_transaction</prop>
      <prop key=”hibernate.transaction.factory_class”>org.hibernate.transaction.JDBCTransactionFactory</prop>
      <prop key=”hibernate.transaction.auto_close_session”>false</prop>
    </props>
  </property>
  <property name=”annotatedPackages”>
    <list>
      <value>forth.model</value>
    </list>
  </property>
  <property name=”annotatedClasses”>
    <list>
      <value>zbwei.model.ModelName</value>
    </list>
  </property>
  </bean>
</beans>

<?xml version=”1.0″ encoding=”UTF-8″?>
<project name=”Forth” default=”compile” basedir=”.”>
  <property name=”build.dir” value=”build” />
  <property name=”build.dist.dir” value=”${build.dir}/dist” />
  <property name=”build.main.dir” value=”${build.dir}/main” />
  <property name=”build.test.dir” value=”${build.dir}/test” />
  <property name=”build.test.output.dir” value=”${build.dir}/test-output” />
  <property name=”build.test.report.dir” value=”${build.dir}/test-report” />
  <property name=”src.dir” value=”src” />
  <property name=”test.dir” value=”test” />
  <property name=”lib.dir” value=”lib” />
  <property name=”ext.dir” value=”ext” />
  <property name=”web.dir” value=”web” />

  <path id=”classpath”>
    <pathelement location=”${build.main.dir}” />
    <pathelement location=”${build.test.dir}” />
    <fileset dir=”${lib.dir}” includes=”*.jar” />
    <fileset dir=”${ext.dir}” includes=”*.jar” />
  </path>

  <target name=”prepare”>
    <mkdir dir=”${build.dist.dir}” />
    <mkdir dir=”${build.main.dir}” />
    <mkdir dir=”${build.test.dir}” />
    <mkdir dir=”${build.test.output.dir}” />
    <mkdir dir=”${build.test.report.dir}” />
  </target>

  <target name=”clean” depends=”prepare”>
    <delete dir=”${build.dir}” />
  </target>

  <target name=”compile” depends=”prepare”>
    <javac srcdir=”${src.dir}” destdir=”${build.main.dir}” encoding=”UTF-8″>
      <classpath refid=”classpath” />
    </javac>
  </target>

  <target name=”compile-test” depends=”compile”>
    <javac srcdir=”${test.dir}” destdir=”${build.test.dir}” encoding=”UTF-8″>
      <classpath refid=”classpath” />
    </javac>
  </target>

  <target name=”test” depends=”compile-test”>
    <taskdef name=”testng”
      classname=”org.testng.TestNGAntTask”
      classpath=”${ext.dir}/testng-5.1.jar” />
    <testng classpathref=”classpath”
      outputdir=”${build.test.output.dir}”
      haltOnfailure=”true”>
      <xmlfileset dir=”test” includes=”testng.xml” />
    </testng>
  </target>

  <target name=”test-report” depends=”test”>
    <junitreport todir=”${build.test.report.dir}”>
      <fileset dir=”${build.test.output.dir}” includes=”**/*.xml” />
      <report format=”noframes” todir=”${build.test.report.dir}” />
    </junitreport>
  </target>

  <target name=”pack-main” depends=”compile”>
    <jar destfile=”${build.dist.dir}/setup.jar”>
      <manifest>
        <attribute name=”Main-Class” value=”Installer” />
        <attribute name=”Class-Path” value=”. server.jar” />
      </manifest>
    </jar>
    <jar destfile=”${build.dist.dir}/server.jar”>
      <fileset dir=”${build.main.dir}” />
    </jar>
    <jar destfile=”${build.dist.dir}/web.war”>
      <fileset dir=”${web.dir}” />
    </jar>
 </target>

  <target name=”pack-test” depends=”compile-test”>
    <jar destfile=”${build.dist.dir}/test.jar”>
      <fileset dir=”${build.test.dir}” />
    </jar>
  </target>

  <target name=”dist” depends=”pack-main, pack-test”>
    <copy todir=”${build.dist.dir}”>
      <fileset dir=”.” includes=”resource/*” />
      <fileset dir=”.” includes=”config/*” />
    </copy>
  </target>
</project>

build/dist/ - 封裝成佈署用的檔案
build/main/ - 主程式class檔
build/test/ - 測試程式class檔
build/test-output/ - TestNG輸出
build/test-report/ - JUnitReport
config/ - 設定檔
classes/ - Eclipse產生的class檔
ext/ - 其它JAR檔，例如ProGuard、yGuard
lib/ - 程式庫JAR檔
resource/ - 資源檔
src/ - 主程式原始碼
test/ - 測試程式原始碼
web/ - 網頁
web/WEB-INF/

在Java中的Date是以long記錄時間，單位是ms，0表示1970-01-01 00:00:00 GMT，而Delphi的TDateTime則是以double記錄時間，0.0表示1899-12-30 00:00:00，整數部分代表從前述時間到某個日期所經過的天數，小數部分乘以86400代表該日經過的秒數。

從1899年12月30日到1970年1月1日，共計25569日，每日計有86400000ms，因此要把Java的時間轉成Delphi的格式可用下列程式：

static final double DAYS_BETWEEN_18991230_AND_19700101 = 25569;
static final double MILLISECONDS_PER_DAY = 86400000;

public static double javaTimeToDelphiTime(final Date time) {
    return (time.getTime() + TIME_ZONE_OFFSET_MILLIS) / MILLISECONDS_PER_DAY + DAYS_BETWEEN_18991230_AND_19700101;
}

經過計算得到的時間就可以直接給在Delphi使用。要將時間換算成Java格式可用：

public static Date delphiTimeToJavaTime(final double time) {
    return new Date((long)((time - DAYS_BETWEEN_18991230_AND_19700101) * MILLISECONDS_PER_DAY - TIME_ZONE_OFFSET_MILLIS));
}

以上就是Java的Date和Delphi的TDateTime的暴力法轉換方式。

在命令列指定使用的keystore， client端：

java -Djavax.net.ssl.trustStore=mykeystore -Djavax.net.ssl.trustStorePassword=123456 Client

server端：

java -Djavax.net.ssl.keyStore=mykeystore -Djavax.net.ssl.keyStorePassword=123456 Server

在程式中設定使用的keystore：

char[] passphrase = "123456".toCharArray();

KeyStore ks = KeyStore.getInstance("JKS");
ks.load(new FileInputStream("mykeystore"), passphrase);

KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509");
kmf.init(ks, passphrase);

TrustManagerFactory tmf = TrustManagerFactory.getInstance("SunX509");
tmf.init(ks);

SSLContext ctx = SSLContext.getInstance("TLS");
ctx.init(kmf.getKeyManagers(), tmf.getTrustManagers(), null);

// client端
Socket socket = ctx.getServerSocketFactory().createServerSocket(port);
// server端
ServerSocket serverSocket = ctx.getSocketFactory().createSocket("hostname", port);

原本要在同一個context執行2個以上的Tapestry程式時，必須在application specification補上不少page的資訊，不過，現在有方便的做法了。檔案架構：

/app1/Home.html
/WEB-INF/app1/app1.application

/app2/Home.html
/WEB-INF/app2/app2.application

app1和app2是servlet名稱，所以在web.xml中要設定：

<servlet>
  <servlet-name>app1</servlet-name>
  <servlet-class>org.apache.tapestry.ApplicationServlet</servlet-class>
  <load-on-startup>0</load-on-startup>
</servlet>
<servlet>
  <servlet-name>app2</servlet-name>
  <servlet-class>org.apache.tapestry.ApplicationServlet</servlet-class>
  <load-on-startup>0</load-on-startup>
</servlet>
<servlet-mapping>
  <servlet-name>app1</servlet-name>
  <url-pattern>/app1/app</url-pattern>
</servlet-mapping>
<servlet-mapping>
  <servlet-name>app2</servlet-name>
  <url-pattern>/app2/app</url-pattern>
</servlet-mapping>

使用app1：http://hostname/app1/app

使用app2：http://hostname/app2/app