程式師世界 >> 編程語言 >> JAVA編程 >> 關於JAVA >> 小試Hessian實現Webservice

小試Hessian實現Webservice

編輯：關於JAVA

Hessian是一個輕量級的remoting on http工具,采用的是Binary RPC協議，所以它很適合於發送二進制數據,同時又具有防火牆穿透能力。Hessian一般是通過Web應用來提供服務，因此非常類似於平時我們用的WebService。只是它不使用SOAP協議,但相比webservice而言更簡單、快捷。

Hessian官網：http://hessian.caucho.com/

Hessian可通過Servlet提供遠程服務，需要將匹配某個模式的請求映射到Hessian服務。也可Spring框架整合，通過它的DispatcherServlet可以完成該功能，DispatcherServlet可將匹配模式的請求轉發到Hessian服務。Hessian的server端提供一個servlet基類, 用來處理發送的請求，而Hessian的這個遠程過程調用，完全使用動態代理來實現的,，建議采用面向接口編程，Hessian服務通過接口暴露。

Hessian處理過程示意圖：

客戶端——>序列化寫到輸出流——>遠程方法(服務器端)——>序列化寫到輸出流 ——>客戶端讀取輸入流——>輸出結果

下面詳細介紹最常用的兩種方式實現Hessian提供webservice：

純Hessian實現

配合Spring框架實現

在開始之前當然需要到官網上下載相關的lib包，放入項目的/WEB-INF/lib/下

【一】、純Hessian實現步驟：

1.基本代碼

首先編寫一個服務的接口類：HelloHessian.Java

Java代碼

package michael.hessian;     
import Java.util.List;     
import Java.util.Map;     
    
/**    
 * @author michael    
 *     
 */    
public interface HelloHessian {     
    
    String sayHello();     
    
    MyCar getMyCar();     
    
    List myLoveFruit();     
    
    Map myBabays();     
    
}

一個java bean文件MyCar.Java:

Java代碼

package michael.hessian;     
    
import Java.io.Serializable;     
    
/**    
 * @author michael    
 *     
 */    
public class MyCar implements Serializable {     
    
    /**    
     *     
     */    
    private static final long serialVersionUID = 4736905401908455439L;     
    
    private String carName;     
    
    private String carModel;     
    
    /**    
     * @return the carName    
     */    
    public String getCarName() {     
        return carName;     
    }     
    
    /**    
     * @return the carModel    
     */    
    public String getCarModel() {     
        return carModel;     
    }     
    
    /**    
     * @param pCarName the carName to set    
     */    
    public void setCarName(String pCarName) {     
        carName = pCarName;     
    }     
    
    /**    
     * @param pCarModel the carModel to set    
     */    
    public void setCarModel(String pCarModel) {     
        carModel = pCarModel;     
    }     
    
    /**    
     * @see Java.lang.Object#toString()    
     * @return    
     */    
    @Override    
    public String toString() {     
        return "my car name:[" + this.carName + "] model:[" + this.carModel     
                + "].";     
    }     
    
}

服務端接口的實現類：HelloHessianImpl.Java

Java代碼

package michael.hessian.impl;     
    
import Java.util.ArrayList;     
import Java.util.HashMap;     
import Java.util.List;     
import Java.util.Map;     
    
import michael.hessian.HelloHessian;     
import michael.hessian.MyCar;     
    
/**    
 * @author michael    
 *     
 */    
public class HelloHessianImpl extends HessianServlet implements HelloHessian {     
    
    public MyCar getMyCar() {     
        MyCar car = new MyCar();     
        car.setCarName("阿斯頓·馬丁");     
        car.setCarModel("One-77");     
        return car;     
    }     
    
    public Map myBabays() {     
        Map map = new HashMap();     
        map.put("son", "孫吳空");     
        map.put("daughter", "孫小美");     
        return map;     
    }     
    
    public List myLoveFruit() {     
        List list = new ArrayList();     
        list.add("apple");     
        list.add("kiwi");     
        list.add("orange");     
        return list;     
    }     
    
    public String sayHello() {     
        return "welcom to Hessian";     
    }     
    
}

2.配置文件web.XML修改

在web.XML配置文件裡增加如下信息：

XML代碼

<servlet>    
        <servlet-name>HelloHessianservlet-name>    
        <servlet-class>    
            com.caucho.hessian.server.HessianServlet     
        servlet-class>    
        <init-param>    
            <param-name>home-classparam-name>    
            <param-value>michael.hessian.impl.HelloHessianImplparam-value>    
        init-param>    
        <init-param>    
            <param-name>home-apiparam-name>    
            <param-value>michael.hessian.HelloHessianparam-value>    
        init-param>    
        <load-on-startup>1load-on-startup>    
    servlet>    
    <servlet-mapping>    
        <servlet-name>HelloHessianservlet-name>    
        <url-pattern>/HessianServiceurl-pattern>    
    servlet-mapping>    
    <servlet-mapping>

3.Java客戶端驗證

Java代碼

package michael.hessian.clIEnt;     
    
import Java.Net.MalformedURLException;     
import Java.util.Map;     
    
import michael.hessian.HelloHessian;     
import michael.hessian.MyCar;     
    
import com.caucho.hessian.clIEnt.HessianProxyFactory;     
    
/**    
 * @author michael    
 *    
 */    
public class HessianClIEntTest {     
    
    /**    
     * @param args    
     */    
    public static void main(String[] args) {     
        String url = "http://localhost:8082/J2EE_sJSky/HessianService";     
        HessianProxyFactory factory = new HessianProxyFactory();     
        try {     
            HelloHessian hello = (HelloHessian) factory.create(     
                    HelloHessian.class, url);     
            System.out.println(hello.sayHello());     
    
            MyCar car = hello.getMyCar();     
            System.out.println(car.toString());     
    
            for (Map.Entry entry : hello.myBabays().entrySet()) {     
                System.out.println(entry.getKey() + "   " + entry.getValue());     
            }     
    
            for (String str : hello.myLoveFruit()) {     
                System.out.println(str);     
            }     
    
        } catch (MalformedURLException e) {     
            e.printStackTrace();     
        }     
    
    }     
    
}

運行結果如下：

Java代碼

welcom to Hessian     
my car name:[阿斯頓·馬丁] model:[One-77].     
daughter   孫小美     
son   孫吳空     
apple     
kiwi     
orange

【二】、spring+hessian 實現服務端：

1.基本代碼見上面的demo

2.修改配置文件

在web.XML，增加內容如下：

XML代碼

<servlet>    
        <servlet-name>springhessianservlet-name>    
        <servlet-class>    
            org.springframework.web.servlet.DispatcherServlet     
        servlet-class>    
            
        1    
        
    
        
        springhessian    
        /springhessian/*

在/WEB-INF/增加一個叫servlet-name-servlet.xml配置文件。該文件的命名有一定的規則，紅色servlet-name需要和web.XML中的springhessian定義的名稱相匹配，比如本例子應叫springhessian-servlet.XML,這樣簡單也不容易出錯。

當然該文件也可以自己任意命名。如果是自定義的文件名稱不符合上述默認的規則，需要在中增加相關屬性，人為指定加載配置文件，否則會報錯。

范例：springhessian-servlet.XML

XML代碼

    
    
    
    
        class="michael.hessian.impl.HelloHessianImpl" />    
        
    <bean name="/helloHessianService"    
        class="org.springframework.remoting.caucho.HessianServiceExporter">    
            
        <property name="service" ref="helloHessianImpl" />    
            
        <property name="serviceInterface"    
            value="michael.hessian.HelloHessian" />    
    bean>    
beans>

3.Java客戶端驗證

和上面的例子相似，只需要把訪問的url替換成新的即可如下：

Java代碼

String url=http://localhost:8082/J2EE_sJSky/springhessian/helloHessianService

運行結果和上面例子一樣。

4.spring配置客戶端

增加一個spring的bean配置文件hessian-clIEnt.XML

XML代碼


>    
<beans>    
    <bean id="helloHessianClIEnt"    
        class="org.springframework.remoting.caucho.HessianProxyFactoryBean">    
        <property name="serviceUrl">    
            <value>    
                http://localhost:8082/J2EE_sJSky/springhessian/helloHessianService     
            value>    
        property>    
        <property name="serviceInterface"    
            value="michael.hessian.HelloHessian" />    
    bean>    
beans>

測試代碼HessianSpringClIEnt.Java：

Java代碼

package michael.hessian.clIEnt;     
    
import Java.util.Map;     
    
import michael.hessian.HelloHessian;     
import michael.hessian.MyCar;     
    
import org.springframework.context.ApplicationContext;     
import org.springframework.context.support.ClassPathXMLApplicationContext;     
    
/**    
 * @author michael    
 *     
 */    
public class HessianSpringClIEnt {     
    
    /**    
     * @param args    
     */    
    public static void main(String[] args) {     
        try {     
            ApplicationContext context = new ClassPathXMLApplicationContext(     
                    "hessian-clIEnt.XML");     
    
            HelloHessian hello = (HelloHessian) context     
                    .getBean("helloHessianClIEnt");     
    
            System.out.println(hello.sayHello());     
    
            MyCar car = hello.getMyCar();     
            System.out.println(car.toString());     
    
            for (Map.Entry entry : hello.myBabays().entrySet()) {     
                System.out.println(entry.getKey() + "   " + entry.getValue());     
            }     
    
            for (String str : hello.myLoveFruit()) {     
                System.out.println(str);     
            }     
        } catch (Exception e) {     
            e.printStackTrace();     
        }     
    
    }     
    
}

運行結果和上面完全一致。

5.com.caucho.hessian.io.HessianProtocolException: expected string at 0x6d異常處理

我在spring+hessian整合測試過程中，客戶端調用時，發生了異常，而服務端錯誤內容如下：

Java代碼

2011-4-25 16:14:44 org.apache.catalina.core.StandardWrapperValve invoke     
嚴重: Servlet.service() for servlet remoting threw exception     
com.caucho.hessian.io.HessianProtocolException: expected string at 0x6d    
    at com.caucho.hessian.io.Hessian2Input.error(Hessian2Input.Java:2882)     
    at com.caucho.hessian.io.Hessian2Input.expect(Hessian2Input.Java:2830)     
    at com.caucho.hessian.io.Hessian2Input.readString(Hessian2Input.Java:1362)     
    at com.caucho.hessian.io.Hessian2Input.readMethod(Hessian2Input.Java:272)     
    at com.caucho.hessian.server.HessianSkeleton.invoke(HessianSkeleton.Java:249)     
    at com.caucho.hessian.server.HessianSkeleton.invoke(HessianSkeleton.Java:221)     
    at org.springframework.remoting.caucho.Hessian2SkeletonInvoker.invoke(Hessian2SkeletonInvoker.Java:67)     
    at org.springframework.remoting.caucho.HessianServiceExporter.handleRequest(HessianServiceExporter.Java:147)     
    at org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter.handle(HttpRequestHandlerAdapter.Java:49)     
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.Java:819)     
    at org.springframework.web.servlet.DispatcherServlet.DOService(DispatcherServlet.Java:754)     
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.Java:399)     
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.Java:364)     
    at javax.servlet.http.HttpServlet.service(HttpServlet.Java:710)     
    at javax.servlet.http.HttpServlet.service(HttpServlet.Java:803)     
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.Java:290)     
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.Java:206)     
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.Java:230)     
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.Java:175)     
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.Java:128)     
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.Java:104)     
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.Java:109)     
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.Java:261)     
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.Java:844)     
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.Java:581)     
    at org.apache.tomcat.util.Net.JIoEndpoint$Worker.run(JIoEndpoint.Java:447)     
    at java.lang.Thread.run(Thread.Java:619)