学习笔记:HttpClient的基本使用
之前公司要求做回报数据处理后结果发送给用户，用户端提供了一个Servlet用来接收数据。因此需要写一个基于Http协议的相关工具进行数据的传输，网上搜索了下，Java关于这方面的技术有两个：一是在JDK中的java.net包中已经提供了访问Http的基本功能，二是Apache Jakarta Common下的一个子项目开源API之HttpClient的子项目，提供高效的、最新的、功能丰富的支持 HTTP 协议的客户端编程工具包。我当然选择Apache的东西啦，于是搜索了相关材料，功能是实现了，不过对于这里面的一些东西还要加以再学习。
安装HttpClient 需要commons-codec-1.3.jar包、commons-httpclient-3.1.jar包、commons-logging-1.0.4.jar包
根据参考来的资料，自己写了一个基本的一个类,提供基本的功能，贴个代码：
/**
*
* <pre>
* 关于Http协议进行操作,提供转发和访问网路地址的相关操作。
* </pre>
*
* @author 陈书挺
* @create 2010-7-23
* @version v1.0
*
* <pre>
* 修改时间 修改人 修改原因
* 2010-7-23 陈书挺 新建类
* </pre>
*
*/
public class HttpOperator {
//URL地址
private String url;
/**
* 根据URL参数创建构造函数<br>
* 默认提交方式为POST提交方式
* @param url URL地址
*/
public HttpOperator(String url){
this.url = url;
}
/**
* 获取页面内容(页面代码),可指定提交方式<br>
* 提交方式取值为:
* SubmitMethod.GET :GET提交方式
* SubmitMethod.POST : POST 提交方式
* @param 提交方式
* @return 页面内容
* @throws IOException
*/
public String getPageContent(SubmitMethod submitMethod) throws IOException{
// 1.创建httpClient实例
HttpClient httpClient = new HttpClient();
if(submitMethod == SubmitMethod.GET){
//2.GetMethod会自动处理转发过程
GetMethod getMethod = new GetMethod(this.url);
return this.getPageContentForGet(httpClient, getMethod);
}else if(submitMethod == SubmitMethod.POST){
PostMethod postMethod = new PostMethod(this.url);
return this.getPageContentForPost(httpClient, postMethod);
}else{
return null;
}
}
/**
* 执行转发 可进行传参数key参数名,value指定参数值
* @param key 参数名
* @param value 参数值
* @return Http状态码
* @throws HttpException
* @throws IOException
*/
public int executeForward(String key , String value) throws HttpException, IOException{
PostMethod postMethod = null;
try{
HttpClient httpClient = new HttpClient();
postMethod = new PostMethod(url);
postMethod.setParameter(key, value);
int statusCode = httpClient.executeMethod(postMethod);
return statusCode;
}catch (Exception e){
throw new IOException(e);
}finally{
postMethod.releaseConnection();
}
}
/**
* 执行转发 可进行传参数集体参数map ,其中Map中的key指定参数名,value指定参数值
* @param map 参数Map对象
* @return Http状态码
* @throws HttpException
* @throws IOException
*/
public int executeForwad(Map<String , String> map) throws HttpException, IOException{
NameValuePair [] nameValue = new NameValuePair[map.size()];
int k = 0;
for(String key : map.keySet()){
nameValue[k].setName(key);
nameValue[k++].setValue(map.get(key));
}
return executeForward(nameValue);
}
/**
* 执行转发 可进行传参数集体参数NameValuePair数组<br>
* 其中NameValuePair对象封装了name 和value属性
* @param parameters NameValuePair对象
* @return Http状态码
* @throws HttpException
* @throws IOException
*/
public int executeForward(NameValuePair[] parameters) throws HttpException,
IOException {
PostMethod postMethod = null;
try {
HttpClient httpClient = new HttpClient();
postMethod = new PostMethod(url);
postMethod.setRequestBody(parameters);
int statusCode = httpClient.executeMethod(postMethod);
return statusCode;
} catch (Exception e) {
throw new IOException(e);
} finally {
postMethod.releaseConnection();
}
}
/**
* 执行转发 将字节数组放入传输管道中进行传输数据
* @param data 要传输的数据
* @return Http状态码
* @throws HttpException
* @throws IOException
*/
public int executeForward(byte[] data) throws HttpException, IOException {
PostMethod postMethod = null;
try {
HttpClient httpClient = new HttpClient();
postMethod = new PostMethod(url);
ByteArrayInputStream bis = new ByteArrayInputStream(data);
InputStreamRequestEntity requestEntity = new InputStreamRequestEntity(bis);
postMethod.setRequestEntity(requestEntity);
int statusCode = httpClient.executeMethod(postMethod);
return statusCode;
} catch (Exception e) {
throw new IOException(e);
} finally {
postMethod.releaseConnection();
}
}
/**
* 执行转发 将字符串类型放入传输管道中进行传输数据
* @param data 要传输的数据
* @return Http状态码
* @throws HttpException
* @throws IOException
*/
public int executeForward(String data) throws HttpException, IOException{
return executeForward(data.getBytes());
}
/**
* 执行转发 将输入流中的数据放入传输管道中进行传输数据
* @param inputStream 输入流
* @return Http状态码
* @throws HttpException
* @throws IOException
*/
public int executeForward(InputStream inputStream) throws HttpException,
IOException {
PostMethod postMethod = null;
try {
HttpClient httpClient = new HttpClient();
postMethod = new PostMethod(url);
InputStreamRequestEntity requestEntity = new InputStreamRequestEntity(inputStream);
postMethod.setRequestEntity(requestEntity);
int statusCode = httpClient.executeMethod(postMethod);
return statusCode;
} catch (Exception e) {
throw new IOException(e);
} finally {
postMethod.releaseConnection();
}
}
/*
* 使用GET方式获取页面内容
* @param httpClient HttpClient对象
* @param getMethod Get提交方式类
* @return 页面内容
* @throws IOException
*/
private String getPageContentForGet(HttpClient httpClient , GetMethod getMethod) throws IOException{
// 使用系统提供的默认恢复策略 重试3次
getMethod.getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
new DefaultHttpMethodRetryHandler());
try {
//3.调用httpClient实例来执行getMethod方法
//返回服务器返回的状态码
int statusCode = httpClient.executeMethod(getMethod);
//如果执行成功
if(statusCode == HttpStatus.SC_OK){
//4.读取内容
byte [] responseBody = getMethod.getResponseBody();
return new String(responseBody);
}
} catch (HttpException e) {
//1.协议不对
//2.返回内容不正常
//3.该异常是无法恢复的
throw new HttpException(e.getMessage());
} catch (IOException e) {
//通常由于网络原因造成
//出现IO异常时候HttpClient会根据制定的恢复策略进行重试
//恢复策略可通过实现HttpMethodRetryHandler接口来实现
throw new IOException(e);
} finally{
// 5.释放连接
getMethod.releaseConnection();
}
return null;
}
/*
* 使用POST方式获取页面内容
* @param httpClient HttpClient对象
* @param postMethod post提交方式类
* @return 页面内容
* @throws IOException
*/
private String getPageContentForPost(HttpClient httpClient , PostMethod postMethod) throws HttpException, IOException{
try{
int statusCode = httpClient.executeMethod(postMethod);
if(statusCode == HttpStatus.SC_OK){
byte [] responseBody = postMethod.getResponseBody();
return new String(responseBody);
}
}catch(IOException e){
throw new IOException(e);
}finally{
postMethod.releaseConnection();
}
return null;
}
}
