安卓上传图片

原理

Android客户端模拟一个HTTP的Post请求到服务器端，服务器端接收相应的Post请求后，返回响应信息给给客户端。

 

PHP服务器

<?php 
　　move_uploaded_file($_FILES[‘file‘][‘tmp_name‘], "./upload/".$_FILES["file"]["name"]); 
?>
 

Android客户端


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package com.example.uploadfile.app;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.os.StrictMode;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class MainActivity extends Activity
{
    private String fileName = "image.jpg";  //报文中的文件名参数
    private String path = Environment.getExternalStorageDirectory().getPath();  //Don‘t use "/sdcard/" here
    private String uploadFile = path + "/" + fileName;    //待上传的文件路径
    private String postUrl = "http://mycloudnote.sinaapp.com/upload.php"; //处理POST请求的页面
    private TextView mText1;
    private TextView mText2;
    private Button mButton;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //"文件路径：\n"+
        mText1 = (TextView) findViewById(R.id.myText1);
        mText1.setText(uploadFile);
        //"上传网址：\n"+
        mText2 = (TextView) findViewById(R.id.myText2);
        mText2.setText(postUrl);
        /* 设置mButton的onClick事件处理 */
        mButton = (Button) findViewById(R.id.myButton);
        mButton.setOnClickListener(new View.OnClickListener()
        {
            public void onClick(View v)
            {
                uploadFile();
            }
        });
    }

    /* 上传文件至Server的方法 */
    private void uploadFile()
    {
        String end = "\r\n";
        String twoHyphens = "--";
        String boundary = "*****";
        try
        {
            URL url = new URL(postUrl);
            HttpURLConnection con = (HttpURLConnection) url.openConnection();
          /* Output to the connection. Default is false,
             set to true because post method must write something to the connection */
            con.setDoOutput(true);
          /* Read from the connection. Default is true.*/
            con.setDoInput(true);
          /* Post cannot use caches */
            con.setUseCaches(false);
          /* Set the post method. Default is GET*/
            con.setRequestMethod("POST");
          /* 设置请求属性 */
            con.setRequestProperty("Connection", "Keep-Alive");
            con.setRequestProperty("Charset", "UTF-8");
            con.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
          /*设置StrictMode 否则HTTPURLConnection连接失败，因为这是在主进程中进行网络连接*/
            StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());
          /* 设置DataOutputStream，getOutputStream中默认调用connect()*/
            DataOutputStream ds = new DataOutputStream(con.getOutputStream());  //output to the connection
            ds.writeBytes(twoHyphens + boundary + end);
            ds.writeBytes("Content-Disposition: form-data; " +
                    "name=\"file\";filename=\"" +
                    fileName + "\"" + end);
            ds.writeBytes(end);
          /* 取得文件的FileInputStream */
            FileInputStream fStream = new FileInputStream(uploadFile);
          /* 设置每次写入8192bytes */
            int bufferSize = 8192;
            byte[] buffer = new byte[bufferSize];   //8k
            int length = -1;
          /* 从文件读取数据至缓冲区 */
            while ((length = fStream.read(buffer)) != -1)
            {
            /* 将资料写入DataOutputStream中 */
                ds.write(buffer, 0, length);
            }
            ds.writeBytes(end);
            ds.writeBytes(twoHyphens + boundary + twoHyphens + end);
          /* 关闭流，写入的东西自动生成Http正文*/
            fStream.close();
          /* 关闭DataOutputStream */
            ds.close();
          /* 从返回的输入流读取响应信息 */
            InputStream is = con.getInputStream();  //input from the connection 正式建立HTTP连接
            int ch;
            StringBuffer b = new StringBuffer();
            while ((ch = is.read()) != -1)
            {
                b.append((char) ch);
            }
          /* 显示网页响应内容 */
            Toast.makeText(MainActivity.this, b.toString().trim(), Toast.LENGTH_SHORT).show();//Post成功
        } catch (Exception e)
        {
            /* 显示异常信息 */
            Toast.makeText(MainActivity.this, "Fail:" + e, Toast.LENGTH_SHORT).show();//Post失败
        }
    }
}
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设置连接（HTTP头） -> 建立TCP连接 -> 设置HTTP正文 -> 建立HTTP连接（正式Post）-> 从返回的输入流读取响应信息

 

1.设置连接（HTTP头）

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URL url = new URL(postUrl);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
/* Output to the connection. Default is false,
set to true because post method must write something to the connection */
con.setDoOutput(true);
/* Read from the connection. Default is true.*/
con.setDoInput(true);
/* Post cannot use caches */
con.setUseCaches(false);
/* Set the post method. Default is GET*/
con.setRequestMethod("POST");
/* 设置请求属性 */
con.setRequestProperty("Connection", "Keep-Alive");
con.setRequestProperty("Charset", "UTF-8");
con.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
复制代码
 

2.建立TCP连接

DataOutputStream ds = new DataOutputStream(con.getOutputStream());  //output to the connection
con.getOutputStream()中会默认调用con.connect()，此时客户端与服务器建立的只是1个TCP连接而非HTTP。

HTTP请求=HTTP头+HTTP正文。

在connect()里面，会根据HttpURLConnection对象的配置值生成HTTP头，所以对con的一切配置都必须在connect()方法之前完成。

 

3.设置HTTP正文

正文通过DataOutputStream写入，只是写入内存而不会发送到网络中去，而是在流关闭时，根据写入的内容生成HTTP正文。

复制代码
ds.writeBytes(twoHyphens + boundary + end);
ds.writeBytes("Content-Disposition: form-data; " +
    "name=\"file\";filename=\"" +
    fileName + "\"" + end);
ds.writeBytes(end);
/* 取得文件的FileInputStream */
FileInputStream fStream = new FileInputStream(uploadFile);
/* 设置每次写入8192bytes */
int bufferSize = 8192;
byte[] buffer = new byte[bufferSize];   //8k
int length = -1;
/* 从文件读取数据至缓冲区 */
while ((length = fStream.read(buffer)) != -1)
{
　　/* 将资料写入DataOutputStream中 */
　　ds.write(buffer, 0, length);
}
ds.writeBytes(end);
ds.writeBytes(twoHyphens + boundary + twoHyphens + end);
/* 关闭流，写入的东西自动生成Http正文*/
fStream.close();
/* 关闭DataOutputStream */
ds.close();
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4.建立HTTP连接（正式Post）

至此，HTTP请求设置完毕，con.getInputStream()中会将请求（HTTP头+HTTP正文）发送到服务器，并返回一个输入流。所以在getInputStream()之前，HTTP正文部分一定要先设置好。

InputStream is = con.getInputStream();  //input from the connection 正式建立HTTP连接
 

5.从返回的输入流读取响应信息

复制代码
int ch;
StringBuffer b = new StringBuffer();
while ((ch = is.read()) != -1)
{
　　b.append((char) ch);
}
/* 显示网页响应内容 */
Toast.makeText(MainActivity.this, b.toString().trim(), Toast.LENGTH_SHORT).show();//Post成功
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布局XML

两个Text和一个Button


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<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${packageName}.${activityClass}">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="New Text"
        android:id="@+id/myText1"
        android:layout_above="@+id/myText2"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="80dp"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="New Text"
        android:id="@+id/myText2"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Upload"
        android:id="@+id/myButton"
        android:layout_marginTop="80dp"
        android:layout_below="@+id/myText2"
        android:layout_centerHorizontal="true"/>
</RelativeLayout>
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AndroidManifest

添加网络权限、SD卡读写权限、挂载文件系统权限。


复制代码
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.uploadfile.app" >

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.uploadfile.app.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    <uses-sdk android:minSdkVersion="9" android:targetSdkVersion="15" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
</manifest>