okhttp3 post 数据打包方法

import okhttp3.OkHttpClient;
import okhttp3.FormBody;
import okhttp3.Request;
import okhttp3.RequestBody;

// HashMap with Params
HashMap<String, String> params = new HashMap<>();
params.put( "Param1", "A" );
params.put( "Param2", "B" );

// Initialize Builder (not RequestBody)
FormBody.Builder builder = new FormBody.Builder();

// Add Params to Builder
for ( Map.Entry<String, String> entry : params.entrySet() ) {
    builder.add( entry.getKey(), entry.getValue() );
}

// Create RequestBody
RequestBody formBody = builder.build();

// Create Request (same)
Request request = new Request.Builder()
        .url( "url" )
        .post( formBody )
        .build();