一、POST與GET的區別：1、GET是從服務器上獲取數據，POST是向服務器傳送數據。2、在客戶端， GET方式在通過URL提交數據，數據在URL中可以看到；POST方式，數據放置在HTML HEADER內提交。3、對於GET方式，服務器端用Request.QueryString獲取變量的值，對於POST方式，服務器端用Request.Form獲取提交的數。4、GET方式提交的數據最多隻能有1024字節，而POST則沒有此限制。5、安全性問題。正如在（2）中提到，使用 GET 的時候，參數會顯示在地址欄上，而 POST 不會。所以，如果這些數據是中文數據而且是非敏感數據，那麼使用 GET ；如果用戶輸入的數據不是中文字符而且包含敏感數據，那麼還是使用 POST為好。
二、Java中的Http編程主要有兩種
1、標準的Java接口
2、標準的Apache接口
三、標準的Java接口編程
1、GET方式
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
public class http_get1 {
// public static final String path =
// "https://192.168.137.103:8080/MyHttp/servlet/LoginAction";
public static final String path = "https://localhost:8080/MyHttp/servlet/LoginAction";
public static String getStringFromStream(InputStream is) {
String str = "";
ByteArrayOutputStream bos = new ByteArrayOutputStream();
int len = 0;
byte[] data = new byte[1024];
if(is!=null){
try {
while ((len = is.read(data)) != -1) {
bos.write(data, 0, len);
}
str = new String(bos.toByteArray(), "utf-8");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return str;
}
public static InputStream useGetMethod(Map map,
String encode) {
InputStream is = null;
StringBuffer sb = new StringBuffer(path);
sb.append("?");
if (map != null && !map.isEmpty()) {
for (Map.Entry entry : map.entrySet()) {
sb.append(entry.getKey()).append("=").append(entry.getValue())
.append("&");
}
sb.deleteCharAt(sb.length() - 1);
System.out.println(sb.toString());
URL url = null;
OutputStream os = null;
try {
url = new URL(sb.toString());
if (url != null) {
HttpURLConnection con = (HttpURLConnection) url
.openConnection();
con.setRequestMethod("GET");
con.setConnectTimeout(3000);
con.setDoInput(true);
con.setDoOutput(true);
os = con.getOutputStream();
os.write(sb.toString().getBytes(encode));
os.close();
if (con.getResponseCode() == 200) {
is = con.getInputStream();
}
}
} catch (Exception e) {
}
}
return is;
}
public static void main(String[] args) {
// TODO Auto-generated method stub
Map map = new HashMap();
map.put("username", "admin");
map.put("password", "1243");
String str = getStringFromStream(useGetMethod(map, "utf-8"));
System.out.println(str);
}
}
2、POST方式
import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.util.HashMap; import java.util.Map; public class http_post1 { // 使用POST請求與GET請求的區別就是POST請求不需要封裝請求路徑，隻需要封裝請求參數 public static InputStream usePostMethod(Map map, String encode) { StringBuffer buffer = new StringBuffer(); InputStream is = null; OutputStream os = null; if (map != null && !map.isEmpty()) { for (Map.Entry entry : map.entrySet()) { try { buffer.append(entry.getKey()).append("=") .append(entry.getValue()) // .append(URLEncoder.encode(entry.getValue(), // encode)) .append("&"); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } buffer.deleteCharAt(buffer.length() - 1); System.out.println(buffer.toString()); } try { URL url = new URL(http_get1.path); if (url != null) { HttpURLConnection con = (HttpURLConnection) url .openConnection(); con.setDoInput(true); con.setDoOutput(true); con.setRequestMethod("POST"); con.setConnectTimeout(3000); byte[] tdata = buffer.toString().getBytes(); // con.setRequestProperty("Content-Type", // "application/x-www-form-urlencoded"); // con.setRequestProperty("Content-Length", // String.valueOf(tdata.length)); os = con.getOutputStream(); os.write(tdata); os.close(); if (con.getResponseCode() == 200) { is = con.getInputStream(); } } } catch (MalformedURLException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } return is; } public static void main(String[] args) { Map map = new HashMap(); map.put("username", "admin"); map.put("password", "123"); System.out.println(http_get1.getStringFromStream(usePostMethod(map, "utf-8"))); } }四、Apache接口
import java.io.InputStream; 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.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.message.BasicNameValuePair; public class http_myapache { public static InputStream useApacheMethod(Map map, String encode) { InputStream is = null; List list = new ArrayList(); for (Map.Entry entry : map.entrySet()) { list.add(new BasicNameValuePair(entry.getKey(), entry.getValue())); } try { // 封裝請求參數 UrlEncodedFormEntity entity = new UrlEncodedFormEntity(list, encode); // 設置請求參數 HttpPost post = new HttpPost(http_get1.path); post.setEntity(entity); // 執行請求 DefaultHttpClient client = new DefaultHttpClient(); HttpResponse response = client.execute(post); // 獲取狀態碼 if (response.getStatusLine().getStatusCode() == 200) { is = response.getEntity().getContent(); } } catch (Exception e) { // TODO: handle exception } return is; } public static void main(String[] args) { Map map = new HashMap(); map.put("username", "admin"); map.put("password", "123"); System.out.println(http_get1.getStringFromStream(useApacheMethod(map, "utf-8"))); } }
總結：
對於普通的Http編程可以選擇GET方式或者POST方式，但對於更高要求的HTTP編程，Apache提供 的標準接口則更為靈活。
附Apache編程的JAR包和XMLPull解析時用到的JAR包：
Apache編程時用到的JAR包： 點擊打開鏈接XMLPull解析時用到的JAR包： 點擊打開鏈接
