okhttp

Okhttp是網(wǎng)絡請求框架。OkHttp主要有Get請求、Post請求等功能。
使用前，需要添加依賴，在當前項目的build.gradle下加入以下代碼：

implementation 'com.squareup.okhttp3:okhttp:3.5.0'

Okhttp的Get請求

使用OkHttp進行Get請求只需要完成以下四步：

獲取OkHttpClient對象

OkHttpClient okHttpClient = new OkHttpClient();

構造Request對象

Request request = new Request.Builder().get().url("https://v0.yiketianqi.com/api?version=v62&appid=12646748&appsecret=SLB1jIr8&city=北京").build();

將Request封裝為Call

Call call = okHttpClient.newCall(request);

根據(jù)需要調用同步或者異步請求方法

//同步調用,返回Response,會拋出IO異常 Response response = call.execute();//異步調用,并設置回調函數(shù) call.enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) {Toast.makeText(OkHttpActivity.this, "get failed", Toast.LENGTH_SHORT).show();}@Overridepublic void onResponse(Call call, final Response response) throws IOException {final String res = response.body().string();runOnUiThread(new Runnable() {@Overridepublic void run() {textView.setText(res);}});} });

OkHttp進行Post請求

使用OkHttp進行Post請求和進行Get請求很類似,只需要以下五步：

獲取OkHttpClient對象

OkHttpClient okHttpClient = new OkHttpClient();

構建FormBody或RequestBody或構架我們自己的RequestBody,傳入?yún)?shù)

//OkHttp進行Post請求提交鍵值對 FormBody formBody = new FormBody.Builder().add("username", "admin").add("password", "admin").build();//OkHttp進行Post請求提交字符串 RequestBody requestBody = RequestBody.create(MediaType.parse("text/plain;charset=utf-8"), "{username:admin;password:admin}");//OkHttp進行Post請求上傳文件 File file = new File(Environment.getExternalStorageDirectory(), "1.png"); if (!file.exists()){Toast.makeText(this, "文件不存在", Toast.LENGTH_SHORT).show(); }else{RequestBody requestBody2 = RequestBody.create(MediaType.parse("application/octet-stream"), file); }//OkHttp進行Post請求提交表單 File file = new File(Environment.getExternalStorageDirectory(), "1.png"); if (!file.exists()){Toast.makeText(this, "文件不存在", Toast.LENGTH_SHORT).show();return; } RequestBody muiltipartBody = new MultipartBody.Builder()//一定要設置這句.setType(MultipartBody.FORM).addFormDataPart("username", "admin")//.addFormDataPart("password", "admin")//.addFormDataPart("myfile", "1.png", RequestBody.create(MediaType.parse("application/octet-stream"), file)).build();

構建Request,將FormBody作為Post方法的參數(shù)傳入

final Request request = new Request.Builder().url("http://www.jianshu.com/").post(formBody).build();

將Request封裝為Call

Call call = okHttpClient.newCall(request);

調用請求,重寫回調方法

call.enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) {Toast.makeText(OkHttpActivity.this, "Post Failed", Toast.LENGTH_SHORT).show();}@Overridepublic void onResponse(Call call, Response response) throws IOException {final String res = response.body().string();runOnUiThread(new Runnable() {@Overridepublic void run() {textView.setText(res);}});} });

gson

GSON在解析json的時候，大體上有2種類型，一種是直接在內存中生成object或array，通過手工指定key來獲取值；另一種是借助javabean來進行映射獲取值。
使用Gson需要添加依賴，在當前項目的build.gradle下加入以下代碼：

implementation 'com.google.code.gson:gson:2.8.6'

實例：解析天氣預報api的json。
首先，需要新建一個實體類，eg:

public class CityWeather {private String city;private String country;private String week;private String wea;@SerializedName("wea_img")private String weaImg;private String tem;private String tem1;private String tem2;private String win;@SerializedName("win_speed")private String winSpeed;@SerializedName("win_meter")private String winMeter;@SerializedName("air_level")private String airLevel;@SerializedName("air_pm25")private String airPm25;@SerializedName("hours")private List<HourWeather> hours;public List<HourWeather> getHourWeatherList() {return hours;}public void setHourWeatherList(List<HourWeather> hourWeatherList) {this.hours = hourWeatherList;}public String getWeaImg() {return weaImg;}public void setWeaImg(String weaImg) {this.weaImg = weaImg;}public String getCity() {return city;}public void setCity(String city) {this.city = city;}public String getCountry() {return country;}public void setCountry(String country) {this.country = country;}public String getWeek() {return week;}public void setWeek(String week) {this.week = week;}public String getWea() {return wea;}public void setWea(String wea) {this.wea = wea;}public String getTem() {return tem;}public void setTem(String tem) {this.tem = tem;}public String getTem1() {return tem1;}public void setTem1(String tem1) {this.tem1 = tem1;}public String getTem2() {return tem2;}public void setTem2(String tem2) {this.tem2 = tem2;}public String getWin() {return win;}public void setWin(String win) {this.win = win;}public String getWinSpeed() {return winSpeed;}public void setWinSpeed(String winSpeed) {this.winSpeed = winSpeed;}public String getWinMeter() {return winMeter;}public void setWinMeter(String winMeter) {this.winMeter = winMeter;}public String getAirLevel() {return airLevel;}public void setAirLevel(String airLevel) {this.airLevel = airLevel;}public String getAirPm25() {return airPm25;}public void setAirPm25(String airPm25) {this.airPm25 = airPm25;}}

其次，需要新建一個用于json解析的類

public class WeatherUtil {public static CityWeather getCityWeather(String str) {Gson gson = new Gson();Type listType = new TypeToken<CityWeather>(){}.getType();CityWeather cityWeather = gson.fromJson(str, listType);return cityWeather;} }

最后，結合okhttp即可解析網(wǎng)絡獲取的json：

public class WeatherActivity extends AppCompatActivity {private List<HourWeather> hourWeatherList;private TextView mWeather;private TextView mCity;private TextView mTem;private TextView mAirLevel;private TextView mTem1;private TextView mTem2;@Overrideprotected void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.weather_activity);initView();OkHttpClient okHttpClient = new OkHttpClient();Request request = new Request.Builder().get().url("https://v0.yiketianqi.com/api?version=v62&appid=12646748&appsecret=SLB1jIr8&city=北京").build();Call call = okHttpClient.newCall(request);//異步調用,并設置回調函數(shù)call.enqueue(new Callback() {@Overridepublic void onFailure(Call call, IOException e) {Toast.makeText(WeatherActivity.this, "get failed", Toast.LENGTH_SHORT).show();}@Overridepublic void onResponse(Call call, final Response response) throws IOException {final String res = response.body().string();runOnUiThread(new Runnable() {@Overridepublic void run() {CityWeather cityWeather = WeatherUtil.getCityWeather(res);mWeather.setText(cityWeather.getWea());mCity.setText(cityWeather.getCity());mTem.setText(cityWeather.getTem());mAirLevel.setText(cityWeather.getAirLevel());mTem1.setText(cityWeather.getTem1());mTem2.setText(cityWeather.getTem2() + "℃");hourWeatherList = cityWeather.getHourWeatherList();int resID = getResources().getIdentifier(cityWeather.getWeaImg() + "_bg" , "mipmap", getPackageName());Glide.with(WeatherActivity.this).asBitmap().load(resID).into(new SimpleTarget<Bitmap>(){@Overridepublic void onResourceReady(Bitmap resource, Transition<? super Bitmap> transition) {Drawable drawable = new BitmapDrawable(resource);mConstraintLayout.setBackground(drawable);}});}});}});}private void initView() {mWeather = findViewById(R.id.weather);mCity = findViewById(R.id.city);mTem = findViewById(R.id.tem);mAirLevel = findViewById(R.id.air_level);mTem1 = findViewById(R.id.tem1);mTem2 = findViewById(R.id.tem2);} }

glide

Glide 是一個圖片加載庫，跟它同類型的庫還有 Picasso、Fresco、Universal-Image-Loader 等。
glide庫的優(yōu)點：

• 加載類型多樣化：Glide 支持 Gif、WebP 等格式的圖片。
• 生命周期的綁定：圖片請求與頁面生命周期綁定，避免內存泄漏。
• 使用簡單(鏈式調用)，且提供豐富的 Api 功能 (如: 圖片裁剪等功能)。
• 高效的緩存策略：

支持多種緩存策略 (Memory 和 Disk 圖片緩存)。

根據(jù) ImageView 的大小來加載相應大小的圖片尺寸。

內存開銷小，默認使用 RGB_565 格式 (3.x 版本)。

使用 BitmapPool 進行 Bitmap 的復用。

首先，使用glide需要添加依賴，在當前項目的build.gradle下加入以下代碼：

implementation 'com.github.bumptech.glide:glide:4.8.0'

其次，在加載圖片時，若需要網(wǎng)絡請求或者本地內存的訪問，需要在當前項目的AndroidManifest.xml中加入請求權限代碼：

//用于網(wǎng)絡請求<uses-permission android:name="android.permission.INTERNET"/>//它可以監(jiān)聽用戶的連接狀態(tài)并在用戶重新連接到網(wǎng)絡時重啟之前失敗的請求<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>//用于硬盤緩存和讀取<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/><uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

glide的使用

Glide.with(MainActivity).load(R.mipmap.image).into(imageView);

• with()方法可以接收Context、Activity或者Fragment類型的參數(shù)。
• load()方法中不僅可以傳入圖片地址，還可以傳入圖片文件File，resource，圖片的byte數(shù)組等。
• into()參數(shù)可以直接寫圖片控件，如需要給其他控件添加背景圖片，則需要：

.into(new SimpleTarget<Bitmap>(){@Overridepublic void onResourceReady(Bitmap resource, Transition<? super Bitmap> transition) {Drawable drawable = new BitmapDrawable(resource);mConstraintLayout.setBackground(drawable);}});

加載本地圖片：

File file = new File(getExternalCacheDir() + "/image.jpg"); Glide.with(this).load(file).into(imageView);

加載應用資源：

int resource = R.drawable.image; Glide.with(this).load(resource).into(imageView);

加載二進制流：

byte[] image = getImageBytes(); Glide.with(this).load(image).into(imageView);

加載Uri對象：

Uri imageUri = getImageUri(); Glide.with(this).load(imageUri).into(imageView);

注意with()方法中傳入的實例會決定Glide加載圖片的生命周期，如果傳入的是Activity或者Fragment的實例，那么當這個Activity或Fragment被銷毀的時候，圖片加載也會停止。如果傳入的是ApplicationContext，那么只有當應用程序被殺掉的時候，圖片加載才會停止。
取消圖片：Glide.with(this).load(url).clear();

總結

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