一、总述
? ? ? ?在Hessian学习笔记之上传文件这一篇中，通过一个实例讲解了如何通过Hessian实现上传文件。Hessian最主要的特征之一就是远程过程调用（Remote Procedure Call，RPC）。下面通过一个简单的实例说明。
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二、实例展示
? ? ?1、环境搭建
? ? ? ? ? 开发工具：eclipse + tomcat。
? ? ? ? ? 服务端：JavaWeb工程。例如，实例中本人创建的JavaDemo工程。
? ? ? ? ? 客户端：Java工程。例如，实例中本人创建的HessianClient工程。
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? ? ?2、代码实现
? ? ? ? ? ?a.实体类： ? ? ? ?
import java.io.Serializable;
import java.util.Date;
public class Person implements Serializable {
private static final long serialVersionUID = 8268991521882061845L;
private int id;
private String name ;
private Long phone ;
private boolean gender;
private double height;
private float weight;
private String[] address;
private Date birthday;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Long getPhone() {
return phone;
}
public void setPhone(Long phone) {
this.phone = phone;
}
public boolean isGender() {
return gender;
}
public void setGender(boolean gender) {
this.gender = gender;
}
public double getHeight() {
return height;
}
public void setHeight(double height) {
this.height = height;
}
public float getWeight() {
return weight;
}
public void setWeight(float weight) {
this.weight = weight;
}
public String[] getAddress() {
return address;
}
public void setAddress(String[] address) {
this.address = address;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String toString(){
return "name:" + this.name + " phone:" + this.phone;
}
}
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? ? ? ? ? ?b.服务端HessianServer接口 ? ? ? ? ??
import java.io.InputStream;
import java.util.List;
import com.zh.hessian.entry.Person;
public interface HessianServer {
public String say();
public String say(String str);
public List<Person> getPerson();
public Person getPersonById(int id);
public boolean upload(String filename,InputStream data);
public byte[] download(String filename);
}
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? ? ? ? ?c.服务端HessianServer接口实现 ? ? ? ??
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Date;
import java.util.List;
import java.util.Random;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.IOUtils;
import com.zh.hessian.entry.Person;
public class HessianServerImpl implements HessianServer {
//上传或下载文件的地址
private static String file_Path = "D:/tools/LearningByMyself/hessian/temp/";
private static Person[] persons = new Person[5];
static {
Random random = new Random();
for(int i=0;i<persons.length;i++){
persons[i] = new Person();
persons[i].setId(i);
persons[i].setGender(random.nextBoolean());
persons[i].setName("name-" + i);
persons[i].setPhone(random.nextLong());
persons[i].setHeight(random.nextDouble());
persons[i].setWeight(random.nextFloat());
persons[i].setAddress(new String[]{"Address" + random.nextInt(),"Address" + random.nextInt()});
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.DATE, i+1);
persons[i].setBirthday(calendar.getTime());
}
}
@Override
public String say() {
return "Hello HessianRPC " + new Date().toString();
}
@Override
public String say(String str) {
return "Welcome" + str;
}
@Override
public List<Person> getPerson() {
return Arrays.asList(persons);
}
@Override
public Person getPersonById(int id) {
for(Person person : persons){
if(person.getId() == id){
return person ;
}
}
return null;
}
@Override
public boolean upload(String filename, InputStream data) {
List<String> temp;
try {
temp = IOUtils.readLines(data);
String filePath = file_Path + filename;
FileUtils.writeLines(new File(filePath), temp);
System.out.println("Upload file to " + filePath);
return true;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
@Override
public byte[] download(String filename) {
String filePath = file_Path + filename;
InputStream data = null;
try {
data = new FileInputStream(filePath);
int size = data.available();
byte[] buffer = new byte[size];
IOUtils.read(data, buffer);
return buffer;
} catch (FileNotFoundException e) {
e.printStackTrace();
return null;
} catch (IOException e) {
e.printStackTrace();
return null;
} finally {
IOUtils.closeQuietly(data);
}
}
}
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? ? ? ? ?d.web.xml配置 ? ? ?
<servlet>
<!-- RPC HessianServlet -->
<servlet-name>hessianRPC</servlet-name>
<servlet-class>com.caucho.hessian.server.HessianServlet</servlet-class>
<!-- 服务端配置 -->
<init-param>
<param-name>service-class</param-name>
<param-value>com.zh.hessian.server.HessianServerImpl</param-value>
</init-param>
<!-- 客户端配置（可选） -->
<init-param>
<param-name>api-class</param-name>
<param-value>com.zh.hessian.server.HessianServer</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>hessianRPC</servlet-name>
<url-pattern>/hessianRPC</url-pattern>
</servlet-mapping>
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? ? ? ? ?e.检验服务端
? ? ? ? ?启动Tomcat后，在浏览器中输入：http://localhost:8080/JavaDemo/hessianRPC，回车后，出现如下信息：
则服务端可用。
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? ? ? ? ?f.文件打包：
? ? ? ? ?将服务端的HessianServer文件和实体类Person打成Jar包，添加到客户端的工程。例如，实例中打成的两个jar包：HessianRPC.jar和Person.jar。
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? ? ? ? ?g.客户端实现? ???
import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import org.apache.commons.io.IOUtils;
import com.caucho.hessian.client.HessianProxyFactory;
import com.zh.hessian.entry.Person;
import com.zh.hessian.server.HessianServer;
public class HessianClient {
//Hessian RPC远程服务url
private static final String url = "http://127.0.0.1:8080/JavaDemo/hessianRPC";
public static void main(String[] args) throws Exception{
//创建HessianProxyFactory实例
HessianProxyFactory factory = new HessianProxyFactory();
//开启方法重载
factory.setOverloadEnabled(true);
//获得Hessian服务的远程引用
HessianServer hessianServer = (HessianServer)factory.create(HessianServer.class, url);
//调用方法
System.out.println("call say():" + hessianServer.say());
System.out.println("call say(\"Tom\"):" + hessianServer.say("Tom"));
System.out.println("call getPerson():");
//调用方法获取集合对象
List<Person> persons = hessianServer.getPerson();
if (null != persons && persons.size() > 0) {
for (Person p : persons) {
System.out.println(p.toString());
}
} else {
System.out.println("No person.");
}
//通过参数调用方法获取对象
int id = 2;
System.out.println(String.format("call getPersonById(%d)", id));
Person person = hessianServer.getPersonById(id);
if (null != person) {
System.out.println(person.toString());
} else {
System.out.println("Id is " + id + " person not exist.");
}
uploadFile(hessianServer);
downloadFile(hessianServer);
}
/**
* 上传文件
* @param hessianServer
*/
public static void uploadFile(HessianServer hessianServer){
String file = "D:/papers/work_opt.txt";//需要上传的文件
String file_path= "D:/tools/LearningByMyself/hessian/temp";//上传文件到服务器的路径
InputStream data = null;
try {
data = new BufferedInputStream(new FileInputStream(file));
if (hessianServer.upload("work_opt.txt", data)) {
System.out.println("Upload file " + file_path + " succeed.");
} else {
System.out.println("Upload file " + file_path + " failed.");
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} finally {
IOUtils.closeQuietly(data);
}
}
/**
* 下载文件
* @param hessianServer
*/
public static void downloadFile(HessianServer hessianServer){
byte[] temp = null ;
String file_name = "work_opt.txt" ;
String download_path = "D:/tools/LearningByMyself/hessian/temp_write/";//文件下载后存放的路径
try {
temp = hessianServer.download(file_name);
if (null != temp) {
FileWriter output = new FileWriter(download_path + file_name);
IOUtils.write(temp, output, "UTF-8");
System.out.println("Download file " + download_path + " succeed.");
output.close();
} else {
System.out.println("Download file " + download_path + " failed.");
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
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三、测试结果
? ??call say():Hello HessianRPC Wed Jul 15 10:50:09 CST 2015
? ? call say("Tom"):WelcomeTom
? ? call getPerson():
? ? name:name-0 phone:838556501517807978
? ? name:name-1 phone:284031862309934267
? ? name:name-2 phone:-1412022783575136070
? ? name:name-3 phone:-6202617782412451628
? ? name:name-4 phone:6912293883557709050
? ? call getPersonById(2)
? ? name:name-2 phone:-1412022783575136070
? ? Upload file D:/tools/LearningByMyself/hessian/temp succeed.
? ? Download file D:/tools/LearningByMyself/hessian/temp_write/ succeed.
? ??
? ? 最后在对应的路径下找到上传和下载的文件。例如，实例中的work_opt.txt文件，上传文件：D:\tools\LearningByMyself\hessian\temp，下载文件：D:\tools\LearningByMyself\hessian\temp_write。
原文：http://zh-workhard-java.iteye.com/blog/2227445