The Runtime framework practice of the Java class library during the Android App
The Runtime framework practice of the Java class library during the Android App
Summary: This article will introduce how to achieve related functions through the starting process of the Android application, how to achieve related functions through the Runtime framework of the Java library.We will discuss the basic concepts and usage of the Runtime framework, and provide a complete programming code and related configuration examples.
introduction:
In Android development, starting the application is a key process.During the launch of the application, we usually perform some necessary operations, such as initialized databases, check updates, etc.These operations may take a long time, and it should be completed before the interface display to provide a good user experience.To achieve these operations, we can use Java's Runtime framework.
1. The concept and usage of the Runtime framework:
Runtime is a class provided by Java to represent the runtime environment of the application.Through the Runtime class, we can perform some system -related operations, such as executing commands and obtaining system information.During the startup process of Android applications, we can use the Runtime framework to perform some time -consuming operations to ensure that the application is completed before the display interface.
When using the Runtime framework, we need the following steps:
1. Get Runtime object:
We can use the static method of the Runtime class `getruntime ()` to obtain a Runtime object representing the current runtime environment.For example:
Runtime runtime = Runtime.getRuntime();
2. execute command:
Through the `Exec () method of the Runtime object, we can execute the system command.This method will return a process object, and we can obtain the results of the command execution through this object.For example, if we want to execute a shell command when the application starts, it can be done:
Process process = runtime.exec("shell command");
3. Set the running environment:
Through the Runtime object, we can also set the runtime environment of the application.For example, we can set the maximum pile of the application in memory:
Runtime.maxMemory (100 * 1024 * 1024); // Set the maximum pile size of 100MB
In addition to the above methods, the Runtime class also provides some other useful methods, such as `TotalMemory () and` FreeMemory () `to obtain the memory usage of the application.
2. Example of the Runtime framework:
Below is a simple example, showing how to use the Runtime framework during the startup process of Android applications to execute some commands and set the running environment.Suppose we need to check whether the device is rooted when the application starts.
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Check whether the device has rooted when the application starts
checkRoot();
}
private void checkRoot() {
Runtime runtime = Runtime.getRuntime();
try {
Process process = runtime.exec("su");
int exitCode = process.waitFor();
if (exitCode == 0) {
// The device has rooted
// Execute other operations ...
} else {
// The device does not root
// Execute other operations ...
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
In the above example, we call the `CheckRoot () method in the application's` oncreate () method. This method uses the Runtime framework to execute a `su` command to check whether the device has rooted.According to the return value of the command, we can perform other related operations.
3. Related configuration:
In order to use the Runtime framework in Android applications, we need to add corresponding permissions declarations to the manifest file of the application to obtain the permissions of the execution command.In the `AndroidManifest.xml` file, add the following permissions declaration:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
The above permissions statement will allow us to execute the shell command in the application.
in conclusion:
Through this article, we understand how to use the Runtime framework of the Java library during the startup process of Android applications to perform some system -related operations.We understand the concept and usage of the Runtime framework, and demonstrate how to execute the command and set the runtime environment through an example of how to execute the command and set the runtime environment through an example.It is hoped that this article provides some help for developers to use the Runtime framework during the startup process of Android applications.
