转载：//www.greatytc.com/p/c478d7a20d03
OkHttp可以说是如今最为流行的网络请求框架之一，今天来探究下OkHttp 的使用方法，包括Get 请求、Post 请求、上传下载文件、上传下载图片等功能
在使用OKHttp之前，首先要先了解如下几个比较核心的类：
- OkHttpClient：客户端对象
- Request：访问请求，Post请求中需要包含RequestBody
- RequestBody：请求数据，在Post请求中用到
- Response：即网络请求的响应结果
- MediaType：数据类型，用来表明数据是json，image，pdf等一系列格式
- client.newCall(request).execute()：同步的请求方法
- client.newCall(request).enqueue(Callback callBack)：异步的请求方法，但Callback是执行在子线程中的，因此不能在此进行UI更新操作
在使用前需要先在项目中添加OkHttp的依赖库，在对应的Module的gradle中添加如下语句
compile 'com.squareup.okhttp3:okhttp:3.6.0'
此外，OkHttp内部依赖另一个开源库OkIo，所以也要将它导入进来
compile 'com.squareup.okio:okio:1.11.0'
然后同步项目即可OkHttp的GitHub地址是：OkHttp
OkIo的GitHub地址是：OkIo
一、Get 请求
最常见的网络请求方式可以说就是Get请求了，这里来获取我在简书的个人主页的网页内容
public void get(View view) {
OkHttpClient client = new OkHttpClient();
//构造Request对象
//采用建造者模式，链式调用指明进行Get请求,传入Get的请求地址
Request request = new Request.Builder().get().url("//www.greatytc.com/u/9df45b87cfdf").build();
Call call = client.newCall(request);
//异步调用并设置回调函数
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
ToastUtil.showToast(GetActivity.this, "Get 失败");
}
@Override
public void onResponse(Call call, final Response response) throws IOException {
final String responseStr = response.body().string();
runOnUiThread(new Runnable() {
@Override
public void run() {
tv_result.setText(responseStr);
}
});
}
});
}
需要注意的是，异步调用的回调函数是在子线程当中的，因为需要用Handler或者runOnUiThread来更新UI
这里使用到了一个Toast工具类，用户判断当前线程是否是主线程，是的话则直接弹出Toast，否则利用runOnUiThread来弹出Toast
public class ToastUtil {
public static void showToast(final Activity activity, final String message) {
if ("main".equals(Thread.currentThread().getName())) {
Log.e("ToastUtil", "在主线程");
Toast.makeText(activity, message, Toast.LENGTH_SHORT).show();
} else {
activity.runOnUiThread(new Runnable() {
@Override
public void run() {
Log.e("ToastUtil", "不在主线程");
Toast.makeText(activity, message, Toast.LENGTH_SHORT).show();
}
});
}
}
}
此外，在回调函数的以下方法中
public void onResponse(Call call, final Response response)
如果希望获得返回的是字符串，则可以使用
response.body().string()
如果需要的是字节数组，则使用
response.body().bytes()
如果需要的是输入流，则使用
response.body().byteStream()
二、Post 类型
在OkHttp中用Post方法向服务器发送一个请求体时，请求体需要是一个RequestBody。这个请求体可以是：
- key-value：键值对类型
- String：字符串类型
- Form：类似于Html的表单数据提交
- Stream：流类型
- File：文件类型
三、Post 键值对
public void postParameter(View view) {
OkHttpClient client = new OkHttpClient();
//构建FormBody，传入要提交的参数
FormBody formBody = new FormBody
.Builder()
.add("username", "initObject")
.add("password", "initObject")
.build();
final Request request = new Request.Builder()
.url("//www.greatytc.com/")
.post(formBody)
.build();
Call call = client.newCall(request);
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
ToastUtil.showToast(PostParameterActivity.this, "Post Parameter 失败");
}
@Override
public void onResponse(Call call, Response response) throws IOException {
final String responseStr = response.body().string();
ToastUtil.showToast(PostParameterActivity.this, "Code：" + String.valueOf(response.code()));
runOnUiThread(new Runnable() {
@Override
public void run() {
tv_result.setText(responseStr);
}
});
}
});
}
这里来向简书的网站主页提交两个参数值，可以通过Post来实现模拟登录的功能。当然这里只是模拟了Post操作而已，提交参数后会跳转到404页面
在
public void onResponse(Call call, Response response)
方法中通过
response.code()
可以得到整数类型的结果码：404
四、Post 字符串
在上面的例子中Post传递的是参数对，有时候我们会有要传送字符串的需要，比如向服务器发送一个JSON字符串。那么就可以用如下方法：
public void postString(View view) {
OkHttpClient client = new OkHttpClient();
//RequestBody中的MediaType指定为纯文本，编码方式是utf-8
RequestBody requestBody = RequestBody.create(MediaType.parse("text/plain;charset=utf-8"),
"{username:admin;password:admin}");
final Request request = new Request.Builder()
.url("//www.greatytc.com/")
.post(requestBody)
.build();
Call call = client.newCall(request);
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
ToastUtil.showToast(PostStringActivity.this, "Post String 失败");
}
@Override
public void onResponse(Call call, Response response) throws IOException {
final String responseStr = response.body().string();
ToastUtil.showToast(PostStringActivity.this, "Code：" + String.valueOf(response.code()));
runOnUiThread(new Runnable() {
@Override
public void run() {
tv_result.setText(responseStr);
}
});
}
});
}
五、Post 表单
通过查看网站登录页的Html源代码，通常都可以查看到如下格式的登录表单
<form id="fm1" action="" method="post">
<input id="username" name="username" type="text"/>
<input id="password" name="password" type="password"/>
</form>
这里使用到 MuiltipartBody 来构建一个RequestBody，这是 RequestBody 的一个子类，提交表单数据就是利用这个类来实现的
public void postForm(View view) {
OkHttpClient client = new OkHttpClient();
RequestBody requestBody = new MultipartBody.Builder()
.setType(MultipartBody.FORM)
.addFormDataPart("username", "叶应是叶")
.addFormDataPart("password", "叶应是叶")
.build();
final Request request = new Request.Builder()
.url("//www.greatytc.com/")
.post(requestBody)
.build();
Call call = client.newCall(request);
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
ToastUtil.showToast(PostFormActivity.this, "Post Form 失败");
}
@Override
public void onResponse(Call call, Response response) throws IOException {
final String responseStr = response.body().string();
ToastUtil.showToast(PostFormActivity.this, "Code：" + String.valueOf(response.code()));
runOnUiThread(new Runnable() {
@Override
public void run() {
tv_result.setText(responseStr);
}
});
}
});
}
六、Post 流
public void postStreaming(View view) {
final MediaType MEDIA_TYPE_MARKDOWN = MediaType.parse("text/x-markdown; charset=utf-8");
OkHttpClient client = new OkHttpClient();
RequestBody requestBody = new RequestBody() {
@Override
public MediaType contentType() {
return MEDIA_TYPE_MARKDOWN;
}
@Override
public void writeTo(BufferedSink sink) throws IOException {
sink.writeUtf8("Numbers\n");
sink.writeUtf8("-------\n");
for (int i = 2; i <= 997; i++) {
sink.writeUtf8(String.format(" * %s = %s\n", i, factor(i)));
}
}
private String factor(int n) {
for (int i = 2; i < n; i++) {
int x = n / i;
if (x * i == n) return factor(x) + " × " + i;
}
return Integer.toString(n);
}
};
Request request = new Request.Builder()
.url("https://api.github.com/markdown/raw")
.post(requestBody)
.build();
Call call = client.newCall(request);
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
ToastUtil.showToast(PostStreamingActivity.this, "Post Streaming 失败");
}
@Override
public void onResponse(Call call, Response response) throws IOException {
final String responseStr = response.body().string();
ToastUtil.showToast(PostStreamingActivity.this, "Code：" + String.valueOf(response.code()));
runOnUiThread(new Runnable() {
@Override
public void run() {
tv_result.setText(responseStr);
}
});
}
});
}
七、Post 文件
public void postFile(View view) {
OkHttpClient client = new OkHttpClient();
final MediaType MEDIA_TYPE_MARKDOWN = MediaType.parse("text/x-markdown; charset=utf-8");
File file = new File("README.md");
Request request = new Request.Builder()
.url("https://api.github.com/markdown/raw")
.post(RequestBody.create(MEDIA_TYPE_MARKDOWN, file))
.build();
Call call = client.newCall(request);
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
ToastUtil.showToast(PostFileActivity.this, "Post File 失败");
}
@Override
public void onResponse(Call call, Response response) throws IOException {
final String responseStr = response.body().string();
ToastUtil.showToast(PostFileActivity.this, "Code：" + String.valueOf(response.code()));
runOnUiThread(new Runnable() {
@Override
public void run() {
tv_result.setText(responseStr);
}
});
}
});
}
八、下载图片
public void downImage(View view) {
OkHttpClient client = new OkHttpClient();
final Request request = new Request
.Builder()
.get()
.url("http://avatar.csdn.net/B/0/1/1_new_one_object.jpg")
.build();
Call call = client.newCall(request);
call.enqueue(new Callback() {
@Override
public void onFailure(Call call, IOException e) {
ToastUtil.showToast(DownImageActivity.this, "下载图片失败");
}
@Override
public void onResponse(Call call, Response response) throws IOException {
InputStream inputStream = response.body().byteStream();
//将图片显示到ImageView中
final Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
runOnUiThread(new Runnable() {
@Override
public void run() {
iv_result.setImageBitmap(bitmap);
}
});
//将图片保存到本地存储卡中
File file = new File(Environment.getExternalStorageDirectory(), "image.png");
FileOutputStream fileOutputStream = new FileOutputStream(file);
byte[] temp = new byte[128];
int length;
while ((length = inputStream.read(temp)) != -1) {
fileOutputStream.write(temp, 0, length);
}
fileOutputStream.flush();
fileOutputStream.close();
inputStream.close();
}
});
}
指定图片地址并下载成功后，获取图片的输入流，先用Bitmap decodeStream(InputStream is)方法将输入流转为Bitmap然后显示出来，然后将图片保存到本地存储卡根目录下
记得要申请存储卡的写权限
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
