ANDROID supports common questions about the framework of the library document file
ANDROID supports common questions about the framework of the library document file
In Android application development, the use of support libraries is very common.The support library provides many convenient tools and components to help developers build high -quality applications easier.This article will answer some common questions related to Android support library document file framework and provide some related Java code examples.
1. What is Android support library document file framework?
Android supports library document file framework is a tool for generating application documents.It provides a set of categories and methods that can create and organize documents in applications.Documents can include various contents, such as user guidelines, API references, helping documents, etc.Support the library file framework with a flexible way for developers, enabling them to easily create and maintain applications documents.
2. How to integrate the supporting document file framework?
In order to integrate the supporting document file framework, the corresponding support library needs to be added to the project construction file.You can add the dependencies of the support library through Maven or Gradle.For example, add the following dependencies to Gradle:
gradle
implementation 'androidx.documentfile:documentfile:1.0.0'
After adding dependencies, you can import the corresponding class in the code and use the method provided to create and manage documents.
3. How to create a new document?
To create a new document, you can use the method of `documentFile.createfile ().This method accepts document types, document names, and parent directory as parameters, and returns an object of `documentFile.
Here are a sample code to demonstrate how to create a text file called "MyDocument.txt":
String fileName = "MyDocument.txt";
File parentDir = getApplicationContext().getExternalFilesDir(null);
Uri uri = Uri.fromFile(new File(parentDir, fileName));
DocumentFile document = DocumentFile.fromSingleUri(getApplicationContext(), uri);
if (document == null) {
document = DocumentFile.fromTreeUri(getApplicationContext(), uri);
}
if (document == null || !document.exists()) {
document = DocumentFile.fromTreeUri(getApplicationContext(), uri.getParent());
document.createFile("text/plain", fileName);
}
In the above code, we first create an `URI` object to indicate the location of the document to be created.Then, we use the method of `documentfile.fromsingleuri () or` documentfile.fromtreeuri () `method, obtain document files from the` URI `object.If the document does not exist, we use the method of `createfile ()` to create a new document.
4. How to read and write the content of the document?
To read the contents of the document, you can use the `OpenIninputStream () method of the` DocumentFile` object.This method returns a `InputStream`, which can be used to read the content of the document.
Here are a sample code to demonstrate how to read a text file called "Mydocument.txt":
String fileName = "MyDocument.txt";
File parentDir = getApplicationContext().getExternalFilesDir(null);
Uri uri = Uri.fromFile(new File(parentDir, fileName));
DocumentFile document = DocumentFile.fromSingleUri(getApplicationContext(), uri);
if (document != null && document.exists()) {
try {
InputStream inputStream = getContentResolver().openInputStream(document.getUri());
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
// Treatment of each line
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
In the above code, we first create a `URI` object to indicate the location of the document to be read.Then, we use the method of `documentfile.fromsingleuri ()` to obtain document files, and use the `OpenIninputStream ()" method to open the input stream of the document.Finally, we use the `InputStreamReader` and` bufferedReader` to read the content of the document one by one.
To write the contents of the document, you can use the `OpenoutPutstream () method of the` documentFile` object.This method returns a `OutputStream`, which can be used to write the content of the document.
5. How to modify and delete documents?
To modify the contents of the document, you can use the `OpenoutPutstream () method of the` DocumentFile` object to obtain the output stream of the document, and then use the `OutputStream` object to write the content.
Here are a sample code to write the content in a text file called "MyDocument.txt":
String fileName = "MyDocument.txt";
File parentDir = getApplicationContext().getExternalFilesDir(null);
Uri uri = Uri.fromFile(new File(parentDir, fileName));
DocumentFile document = DocumentFile.fromSingleUri(getApplicationContext(), uri);
if (document != null && document.exists()) {
try {
OutputStream outputStream = getContentResolver().openOutputStream(document.getUri());
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream));
writer.write("Hello, World!");
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
In the above code, we first create an `URI` object, indicating the position of the document to be written.Then, we use the method of `documentfile.fromsingleuri ()` to obtain document files, and use the `OpenoutputStream ()` method to open the output stream of the document.Finally, we use the `OutputStreamWriter` and` BuffredWriter` to write the content.
To delete the document, you can use the `DELETE ()" method of the `documentFile` object.
if (document != null && document.exists()) {
document.delete();
}
In the above code, we first check whether the document exists. If it exists, use the `delete ()` method to delete the document.
Summarize:
The above is the answer to some common questions about the Android supporting the document file framework, including how to integrate the content of supporting library document file framework, creation, reading, writing, and deleting documentation.I hope this article will help you understand and use Android to support library document file frameworks.
