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md/安卓app操作文档.pdf

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+安卓app操作文档
+
+一、实现目标
+
+   1. 实现页面按钮跳转页面
+   2. 点击按钮后，页面显示来自JNI的字符串
+
+二、环境搭建
+
+  2.1 jdk安装
+
+  2.2 andriod studio 安装
+
+三、具体实现
+
+3.1 设置页面跳转
+为了实现跳转页面，首先需要创建两个活动：（ MainActivity 主页面）和 SecondActivity （跳转后
+的页面）
+3.11 MainActivity
+
+   package com.example.myapplication;
+import android.content.Intent;
+import android.os.Bundle;
+import android.view.View;
+import android.widget.Button;
+import androidx.appcompat.app.AppCompatActivity;
+
+public class MainActivity extends AppCompatActivity {
+
+       @Override
+       protected void onCreate(Bundle savedInstanceState) {
+
+              super.onCreate(savedInstanceState);
+              setContentView(R.layout.activity_main);
+
+              Button btnNavigate = findViewById(R.id.btnNavigate);
+
+              // 设置按钮点击事件，跳转到SecondActivity
+              btnNavigate.setOnClickListener(new View.OnClickListener() {
+
+                     @Override
+                     public void onClick(View v) {
+
+                             Intent intent = new Intent(MainActivity.this,
+SecondActivity.class);
+
+                             startActivity(intent);
+                     }
+              });
+       }
+}
+
+3.12 SecondActivity
+
+package com.example.myapplication;
+
+import android.os.Bundle;
+import android.view.View;
+import android.widget.Button;
+import android.widget.TextView;
+import androidx.appcompat.app.AppCompatActivity;
+
+public class SecondActivity extends AppCompatActivity {
+
+static {                                  // 加载JNI库
+       System.loadLibrary("native-lib");
+
+}
+
+// 声明JNI方法
+private native String getJNIString();
+
+@Override
+protected void onCreate(Bundle savedInstanceState) {
+
+       super.onCreate(savedInstanceState);
+       setContentView(R.layout.activity_second);
+
+Button btnShowJNI = findViewById(R.id.btnShowJNI);
+TextView textViewFromJNI = findViewById(R.id.jniTextView);
+                 // 设置按钮点击事件，获取并显示JNI字符串
+                 btnShowJNI.setOnClickListener(new View.OnClickListener() {
+
+                         @Override
+                         public void onClick(View v) {
+
+                                // 调用JNI方法并显示结果
+                                textViewFromJNI.setText(getJNIString());
+                         }
+                 });
+          }
+   }
+
+3.2 集成JNI
+3.21 在 native-lib.cpp 中，编写JNI方法以返回字符串
+
+   #include <jni.h>
+   #include <string>
+
+   extern "C" JNIEXPORT jstring JNICALL
+   Java_com_example_myapplication_SecondActivity_getJNIString(JNIEnv* env, jobject
+   /* this */) {
+
+          std::string hello = "Hello from JNI!";
+          return env->NewStringUTF(hello.c_str());
+   }
+
+3.22 CMakeLists.txt编写
+
+   cmake_minimum_required(VERSION 3.10.2)
+
+   # Set project name
+   project("myapplication")
+
+   # Set the path for the source file (make sure the path is correct)
+   add_library(native-lib SHARED
+   E:/CodeProject/AndroidProjects/MyApplication/app/src/main/cpp/native-lib.cpp)
+
+   # Find the log library (important for Android projects)
+   find_library( log-lib
+
+                 log )
+
+   # Link the native library with the log library
+   target_link_libraries( native-lib
+
+                 ${log-lib} )
+
+四、运行结果
+
+4.1 初始运行界面
+点击Page Jump跳转到第二页面
+
+4.2 验证跳转功能
+点击Show JNI String 按钮，成功显示“Hello from JNI!”
+