现在不管什么APP都有个头像，如果你看见没有头像的APP就会感觉非常奇怪，以前头像都是方的，后来就变成圆的，我估计在过个几年就得来个五角星形状的头像，下面我把更换头像的代码写来：

首先我定义了一个非常简单的XML布局，里面两个Button，一个ImageView用来显示头像：

下面我来看看MainActivity代码：

package com.example.changhead;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
@SuppressLint("SdCardPath")public class MainActivity extends Activity implements OnClickListener {
private ImageView ivHead;
//头像显示 private Button btnTakephoto;
//拍照 private Button btnPhotos;
//相册 private Bitmap head;
//头像Bitmap private static String path="/sdcard/myHead/";
//sd路径 @Override protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
}
private void initView() {
//初始化控件 btnPhotos = (Button) findViewById(R.id.btn_photos);
btnTakephoto = (Button) findViewById(R.id.btn_takephoto);
btnPhotos.setOnClickListener(this);
btnTakephoto.setOnClickListener(this);
ivHead = (ImageView) findViewById(R.id.iv_head);
Bitmap bt = BitmapFactory.decodeFile(path + "head.jpg");
//从Sd中找头像，转换成Bitmap if(bt!=null){
@SuppressWarnings("deprecation") Drawable drawable = new BitmapDrawable(bt);
//转换成drawable ivHead.setImageDrawable(drawable);
}
else{
/** * 如果SD里面没有则需要从服务器取头像，取回来的头像再保存在SD中 * */ }
}
@Override public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_photos://从相册里面取照片 Intent intent1 = new Intent(Intent.ACTION_PICK, null);
intent1.setDataAndType(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, "image/*");
startActivityForResult(intent1, 1);
break;
case R.id.btn_takephoto://调用相机拍照 Intent intent2 = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
intent2.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(new File(Environment.getExternalStorageDirectory(), "head.jpg")));
startActivityForResult(intent2, 2);
//采用ForResult打开 break;
default: break;
}
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case 1: if (resultCode == RESULT_OK) {
cropPhoto(data.getData());
//裁剪图片 }
break;
case 2: if (resultCode == RESULT_OK) {
File temp = new File(Environment.getExternalStorageDirectory() + "/head.jpg");
cropPhoto(Uri.fromFile(temp));
//裁剪图片 }
break;
case 3: if (data != null) {
Bundle extras = data.getExtras();
head = extras.getParcelable("data");
if(head!=null){
/** * 上传服务器代码 */ setPicToView(head);
//保存在SD卡中 ivHead.setImageBitmap(head);
//用ImageView显示出来 }
}
break;
default: break;
}
super.onActivityResult(requestCode, resultCode, data);
}
;
/** * 调用系统的裁剪 * @param uri */ public void cropPhoto(Uri uri) {
Intent intent = new Intent("com.android.camera.action.CROP");
intent.setDataAndType(uri, "image/*");
intent.putExtra("crop", "true");
// aspectX aspectY 是宽高的比例 intent.putExtra("aspectX", 1);
intent.putExtra("aspectY", 1);
// outputX outputY 是裁剪图片宽高 intent.putExtra("outputX", 150);
intent.putExtra("outputY", 150);
intent.putExtra("return-data", true);
startActivityForResult(intent, 3);
}
private void setPicToView(Bitmap mBitmap) {
String sdStatus = Environment.getExternalStorageState();
if (!sdStatus.equals(Environment.MEDIA_MOUNTED)) {
// 检测sd是否可用 return;
}
FileOutputStream b = null;
File file = new File(path);
file.mkdirs();
// 创建文件夹 String fileName =path + "head.jpg";
//图片名字 try {
b = new FileOutputStream(fileName);
mBitmap.compress(Bitmap.CompressFormat.JPEG, 100, b);
// 把数据写入文件 }
catch (FileNotFoundException e) {
e.printStackTrace();
}
finally {
try {
//关闭流 b.flush();
b.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
}
}

对了不要忘记加权限：