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1>：使用get方式获取服务器端的一张图片，放在本地==》获取服务器的东西用get方式更好
package get; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; public class HttpUtil { /** * 使用get方式获取服务器端的一张图片 * @throws IOException */ public static InputStream getInputStream(String path) throws IOException { URL url = new URL(path); HttpURLConnection con = (HttpURLConnection) url.openConnection(); //设置请求方式 con.setRequestMethod("GET");//默认请求方式是get //设置连接超时时间 con.setConnectTimeout(5000); //设置可以从服务器端读取数据 con.setDoInput(true);//默认值就是true InputStream in = null; //判断服务器端的响应码是否是200 if(con.getResponseCode()==200) { in = con.getInputStream(); } return in; } public static void makeImg(InputStream in) throws IOException { FileOutputStream fos = new FileOutputStream("file\\img.jpg"); byte[] b = new byte[1024]; int len = 0; //读取服务器返回的图片数据 while ((len = in.read(b))!=-1) { fos.write(b,0,len); } fos.close(); in.close(); } }
package get; import java.io.IOException; public class Test { public static void main(String[] args) throws IOException { String path ="http://localhost:9999/day16/img2.jpg"; HttpUtil.makeImg(HttpUtil.getInputStream(path)); } }
2：使用post方式提交用户名和密码，并获取服务器端的验证结果==》需要返回数据就用post，服务器端代码上篇博客中有
package post; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.util.ArrayList; import java.util.List; import java.util.Map; import org.apache.http.HttpResponse; import org.apache.http.NameValuePair; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.message.BasicNameValuePair; public class HttpUtil { public static String sendByPost(String path,Map<String,String> params,String encode) throws ClientProtocolException, IOException { //先把要提交的每对儿数据封装成NameValuePair类型的 List<NameValuePair> list = new ArrayList<NameValuePair>(); for(Map.Entry<String, String> en:params.entrySet()) { list.add(new BasicNameValuePair(en.getKey(),en.getValue())); } //把要提交的数据组织成提交的格式 UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, encode); //创建提交方式对象 HttpPost post = new HttpPost(path); post.setEntity(entity); //创建执行提交的对象 HttpClient client = new DefaultHttpClient(); //执行提交 HttpResponse response = client.execute(post); if(response.getStatusLine().getStatusCode()==200) { InputStream in = response.getEntity().getContent(); return getResult(in,encode); } return null; } private static String getResult(InputStream in, String encode) throws IOException { ByteArrayOutputStream bos = new ByteArrayOutputStream(); byte[] arr = new byte[1024]; int len = 0; while((len = in.read(arr))!=-1) { bos.write(arr,0,len); } return new String(bos.toByteArray(),encode); } }
package post; import java.io.IOException; import java.util.HashMap; import java.util.Map; public class Test { /** * @param args * @throws IOException */ public static void main(String[] args) throws IOException { Map<String,String> params = new HashMap<String, String>(); params.put("username", "李鹏"); params.put("pwd","123456"); String path = "http://localhost:9999/day16/servlet/LoginServlet"; String encode= "utf-8"; System.out.println(HttpUtils.sendByPost(path, params, encode)); } }
3：使用apache中jar包提供的简介方法提交用户名和密码，并获取服务器端的验证结果
package apache; import java.io.ByteArrayOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.UnsupportedEncodingException; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import org.apache.http.HttpResponse; import org.apache.http.NameValuePair; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.message.BasicNameValuePair; public class HttpUtil { public static String sendByPost(String path,HashMap<String,String> params,String encode) throws ClientProtocolException, IOException { //先把要提交的每对儿数据封装成NameValuePair类型的 List<NameValuePair> list = new ArrayList<NameValuePair>(); for(Map.Entry<String, String> en:params.entrySet()) { list.add(new BasicNameValuePair(en.getKey(),en.getValue())); } //把要提交的数据组织成提交的格式 UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, encode); //创建提交方式对象 HttpPost post = new HttpPost(path); post.setEntity(entity); //创建执行提交的对象 HttpClient client = new DefaultHttpClient(); //执行提交 HttpResponse response = client.execute(post); if(response.getStatusLine().getStatusCode()==200) { InputStream in = response.getEntity().getContent(); return getResult(in,encode); } return null; } private static String getResult(InputStream in, String encode) throws IOException { ByteArrayOutputStream bos = new ByteArrayOutputStream(); byte[] arr = new byte[1024]; int len = 0; while((len = in.read(arr))!=-1) { bos.write(arr,0,len); } return new String(bos.toByteArray(),encode); } }
package appache; import java.io.IOException; import java.util.HashMap; import java.util.Map; public class Test { /** * @param args * @throws IOException */ public static void main(String[] args) throws IOException { Map<String,String> params = new HashMap<String, String>(); params.put("username", "李鹏"); params.put("pwd","123456"); String path = "http://localhost:9999/day16/servlet/LoginServlet"; String encode= "utf-8"; System.out.println(HttpUtil.sendByPost(path, params, encode)); } }
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原文地址：http://www.cnblogs.com/lipeng0824/p/4725443.html
