Spring v3.0.2 Learning Note 16 - Integrate With Hessian

本文链接：https://blog.youkuaiyun.com/wxhawk/article/details/5963880

本文介绍如何使用 Spring 的 HessianServiceExporter 和 DispatcherServlet 配置远程服务，并提供了一个示例，包括 web.xml 和 spring 配置文件的具体设置。此外还探讨了解决在 WebLogic 服务器上部署时遇到的问题。

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Reference Library

%SPRING%/dist/com.springsource.org.aopalliance-1.0.0.jar%SPRING%/dist/org.springframework.aop-3.0.2.RELEASE.jar
%SPRING%/dist/org.springframework.asm-3.0.4.RELEASE.jar
%SPRING%/dist/org.springframework.beans-3.0.2.RELEASE.jar
%SPRING%/dist/org.springframework.context-3.0.4.RELEASE.jar
%SPRING%/dist/org.springframework.core-3.0.2.RELEASE.jar
%SPRING%/dist/org.springframework.expression-3.0.4.RELEASE.jar
%SPRING%/dist/org.springframework.transaction-3.0.2.RELEASE.jar
%SPRING%/dist/org.springframework.web.servlet-3.0.2.RELEASE
%SPRING%/dist/org.springframework.web-3.0.4.RELEASE.jar
%SPRING_DEP%/org.apache.commons/com.springsource.org.apache.commons.logging/1.1.1/com.springsource.org.apache.commons.logging-1.1.1.jar
%SPRING_DEP%/com.caucho/com.springsource.com.caucho/3.2.1/com.springsource.com.caucho-3.2.1.jar
%SPRING_DEP%/javax.servlet/com.springsource.javax.servlet/2.5.0/com.springsource.javax.servlet-2.5.0.jar

Wiring up the DispatcherServlet for Hessian

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    id="WebApp_ID" version="2.5">
    <display-name>springhessian</display-name>

    <servlet>
        <servlet-name>hessianServices</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet </servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>hessianServices</servlet-name>
        <url-pattern>/remote/* </url-pattern>
    </servlet-mapping>

</web-app>

Using Spring's DispatcherServlet principles, as known from Spring Web MVC usage, you can easily wire up such a servlet exposing your services.

Exposing your beans by using the HessianServiceExporter

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    <context:component-scan base-package="com.spring.hessian.test" />
    <bean id="acctService" class="com.spring.hessian.test.impl.AccountInfoImpl" />
    <bean name="/acctService"
        class="org.springframework.remoting.caucho.HessianServiceExporter">
        <property name="service" ref="acctService" />
        <property name="serviceInterface" value="com.spring.hessian.test.IAccountInfo" />
    </bean>
</beans>

Above configuration should be stored in WEB-INF/hessianServices-servlet.xml
Take note the configuration file name must be hessianServices-servlet.xml.
According to spring manual, the file name is remoting-servlet.xml, I tried it but it could not work.

>>> After several try, found the naming rule is <servlet name defined in web.xml>-servlet.xml.
For example, I defined a servlet named hessianServices, so the configure file will be hessianServices-servlet.xml

Source Code

// interface
package com.spring.hessian.test;

import com.spring.hessian.test.bean.AccountInfo;

public interface IAccountInfo {

    public void createAccount(AccountInfo accountInfo);

    public boolean changeEmail(int accountId, String newEmail);

    public void deleteAccount(int accountId);
}

// implement class
package com.spring.hessian.test.impl;

import org.springframework.stereotype.Service;

import com.spring.hessian.test.IAccountInfo;
import com.spring.hessian.test.bean.AccountInfo;

@Service
public class AccountInfoImpl implements IAccountInfo {

    @Override
    public boolean changeEmail(int accountId, String newEmail) {
       System.out.println("Here is the logic to change email.");
       return false;
    }

    @Override
    public void createAccount(AccountInfo accountInfo) {
       System.out
               .println("Here is the logic to create account with account info = "
                       + accountInfo.toString());
    }

    @Override
    public void deleteAccount(int accountId) {
       System.out.println("Here is the logic to delete account with ID = "
               + accountId);
    }

}

// domain class
package com.spring.hessian.test.bean;

import java.io.Serializable;

public class AccountInfo implements Serializable {

    private static final long serialVersionUID = 5308953586718817188L;
    private int accountId;
    private String userName;
    private String password;
    private String email;

    public AccountInfo() {
        super();
    }

    public AccountInfo(int accountId, String userName, String password,
            String email) {
        super();
        this.accountId = accountId;
        this.userName = userName;
        this.password = password;
        this.email = email;
    }

    public int getAccountId() {
        return accountId;
    }

    public void setAccountId(int accountId) {
        this.accountId = accountId;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String toString() {
        return "AccountInfo:[id]=" + this.accountId + ",[userName]="
                + this.userName + ",[pwd]=" + this.password + ",[email]="
                + this.email;
    }

}

// Junit test
package com.spring.hessian.test;

import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test;

import com.caucho.hessian.client.HessianProxyFactory;
import com.spring.hessian.test.bean.AccountInfo;

public class HessianTester {

    @BeforeClass
    public static void setUpBeforeClass() throws Exception {
    }

    @AfterClass
    public static void tearDownAfterClass() throws Exception {
    }

    @Test
    public void test() throws Exception {
        String url = "http://localhost:8080/springhessian/remote/acctService";
        HessianProxyFactory factory = new HessianProxyFactory();
        IAccountInfo accountInfo = (IAccountInfo) factory.create(
                IAccountInfo.class, url);
        AccountInfo account = new AccountInfo(125, "myName", "myPwd",
                "abc@email.com");
        accountInfo.createAccount(account);
        accountInfo.changeEmail(126, "def@email.com");
        accountInfo.deleteAccount(129);
    }
}

From tomcat console ,we can see the output if running above junit test case.

Here is the logic to create account with account info = AccountInfo:[id]=125,[userName]=myName,[pwd]=myPwd,[email]=abc@email.com
Here is the logic to change email.
Here is the logic to delete account with ID = 129

未解决的问题

以上代码和配置在tomcat中一切正常，但是移到weblogic v10.3下，当调用第一个远程方法后总会碰到空指针异常
<Oct 29, 2010 1:42:20 PM SGT> <Error> <Kernel> <BEA-000802> <ExecuteRequest failed
java.lang.NullPointerException.
java.lang.NullPointerException
        at weblogic.utils.http.HttpChunkInputStream.initChunk(HttpChunkInputStream.java:66)
        at weblogic.utils.http.HttpChunkInputStream.skip(HttpChunkInputStream.java:197)
        at weblogic.utils.http.HttpChunkInputStream.skipAllChunk(HttpChunkInputStream.java:371)
        at weblogic.servlet.internal.ServletInputStreamImpl.ensureChunkedConsumed(ServletInputStreamImpl.java:30)
        at weblogic.servlet.internal.ServletRequestImpl.skipUnreadBody(ServletRequestImpl.java:192)
        Truncated. see log file for complete stacktrace
>

到现在仍没找到原因，不得已还是采用hessian的配置方式
<servlet>
<servlet-name>HessianServlet</servlet-name>
<servlet-class>com.caucho.hessian.server.HessianServlet</servlet-class>
<init-param>
   <param-name>home-class</param-name>
   <param-value>com.spring.hessian.test.impl.AccountInfoImpl</param-value>
</init-param>
<init-param>
   <param-name>home-api</param-name>
   <param-value>com.spring.hessian.test.IAccountInfo</param-value>
</init-param>
</servlet>

<servlet-mapping>
<servlet-name>HessianServlet</servlet-name>
<url-pattern>/remote2</url-pattern>
</servlet-mapping>

客户端改用这个URL "http://<host>:<port>/hessian/remote2" 在weblogic下可得正确结果。

如果采用hessian的配置方式，以下依赖包就不再需要了
%SPRING%/dist/org.springframework.web.servlet-3.0.2.RELEASE
%SPRING%/dist/org.springframework.web-3.0.4.RELEASE.jar

以下配置文件不再需要
WEB-INF/hessianServices-servlet.xml

web.xml内容改为：
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
    id="WebApp_ID" version="2.5">
    <display-name>springhessian</display-name>

    <servlet>
        <servlet-name>HessianServlet</servlet-name>
        <servlet-class>com.caucho.hessian.server.HessianServlet</servlet-class>
        <init-param>
            <param-name>home-class</param-name>
            <param-value>com.spring.hessian.test.impl.AccountInfoImpl</param-value>
        </init-param>
        <init-param>
            <param-name>home-api</param-name>
            <param-value>com.spring.hessian.test.IAccountInfo</param-value>
        </init-param>
    </servlet>

    <servlet-mapping>
        <servlet-name>HessianServlet</servlet-name>
        <url-pattern>/remote2</url-pattern>
    </servlet-mapping>
</web-app>

WEB-INF/classes 需要spring的配置文件，内容为：
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    <context:component-scan base-package="com.spring.hessian.test" />
</beans>

为了部属到weblogic,还需要配置文件WEB-INF/weblogic.xml，其内容为：
<?xml version='1.0' encoding='UTF-8'?>
<weblogic-web-app xmlns="http://www.bea.com/ns/weblogic/weblogic-web-app"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.bea.com/ns/weblogic/weblogic-web-app http://www.bea.com/ns/weblogic/weblogic-web-app/1.0/weblogic-web-app.xsd">
    
    <session-descriptor>
        <persistent-store-type>replicated_if_clustered</persistent-store-type>
        <sharing-enabled>true</sharing-enabled>
    </session-descriptor>
     
    <container-descriptor>
        <prefer-web-inf-classes>true</prefer-web-inf-classes>
    </container-descriptor>
        
    <context-root>/hessian</context-root>

</weblogic-web-app>