如何使用IDroid ORM框架访问SQLite数据库及实现增删改查与建表

Alright, let's dive into using the IDroid ORM framework for SQLite database interactions—covering table creation and all CRUD operations. I’ve worked with this framework on a couple of Android projects, so I’ll walk you through practical, easy-to-follow steps.

First, add the IDroid dependency to your app-level build.gradle file (use the latest stable version available):

implementation 'com.github.yuweiguocn:IDroid:v1.0.1'

Then initialize IDroid in your Application class (this ensures it's ready to use across your app):

public class MyApp extends Application {
    @Override
    public void onCreate() {
        super.onCreate();
        IDroid.init(this);
    }
}

Don’t forget to declare your Application class in AndroidManifest.xml.

IDroid uses annotation-based entity classes to map to SQLite tables. Let’s create a User entity for example:

@Table(name = "user") // Maps to a table named "user" in SQLite
public class User {
    @PrimaryKey(autoGenerate = true) // Auto-incrementing primary key
    private long id;
    
    @Column(name = "username") // Maps to a column named "username"
    private String username;
    
    @Column(name = "age")
    private int age;
    
    @Column(name = "email")
    private String email;

    // *Critical*: IDroid requires a no-arg constructor for reflection
    public User() {}

    // Overloaded constructor for convenience (optional)
    public User(String username, int age, String email) {
        this.username = username;
        this.age = age;
        this.email = email;
    }

    // Getters and Setters (required for IDroid to access fields)
    public long getId() { return id; }
    public void setId(long id) { this.id = id; }
    public String getUsername() { return username; }
    public void setUsername(String username) { this.username = username; }
    public int getAge() { return age; }
    public void setAge(int age) { this.age = age; }
    public String getEmail() { return email; }
    public void setEmail(String email) { this.email = email; }
}

IDroid will automatically create the table when you first interact with it. If you need to manually trigger table creation (for edge cases), use:

IDroid.getDb().createTable(User.class);

Single Record Insert #

Use the save() method to insert a single entity. It returns the auto-generated primary key ID:

User newUser = new User("john_doe", 28, "john@example.com");
long insertedId = IDroid.getDb().save(newUser);

Batch Insert #

For inserting multiple records at once, use saveBatch()—it returns the number of successfully inserted records:

List<User> userList = new ArrayList<>();
userList.add(new User("jane_smith", 25, "jane@example.com"));
userList.add(new User("bob_brown", 30, "bob@example.com"));

int insertedCount = IDroid.getDb().saveBatch(userList);

Update by Primary Key #

To update an existing record, set the primary key (so IDroid knows which row to target) and call update():

User updatedUser = new User();
updatedUser.setId(1); // Target the user with ID 1
updatedUser.setAge(29); // Update only the age field
updatedUser.setEmail("john_new@example.com"); // Update email too

int updatedCount = IDroid.getDb().update(updatedUser);

Conditional Update #

Use the UpdateBuilder to update rows based on a condition (e.g., update all users over 25 with a new email):

int updatedCount = IDroid.getDb().update(User.class)
    .set("email", "updated@example.com")
    .where("age > ?", 25)
    .execute();

Delete by Primary Key #

Similar to updates, set the primary key on an entity and call delete():

User userToDelete = new User();
userToDelete.setId(1); // Delete the user with ID 1

int deletedCount = IDroid.getDb().delete(userToDelete);

Conditional Delete #

Delete rows matching a condition (e.g., delete all users under 18):

int deletedCount = IDroid.getDb().delete(User.class)
    .where("age < ?", 18)
    .execute();

Delete All Records #

To wipe an entire table:

IDroid.getDb().deleteAll(User.class);

IDroid’s QueryBuilder makes building complex queries straightforward.

Query Single Record by ID #

User user = IDroid.getDb().findById(User.class, 1);

Query Single Record by Condition #

User user = IDroid.getDb().findFirst(User.class)
    .where("username = ?", "john_doe")
    .execute();

Query All Records #

List<User> allUsers = IDroid.getDb().findAll(User.class);

Conditional Query with Sorting #

Get all users over 25, sorted by age in descending order:

List<User> userList = IDroid.getDb().findList(User.class)
    .where("age > ?", 25)
    .orderBy("age DESC")
    .execute();

Paged Query #

Fetch the second page of results (10 records per page):

List<User> userList = IDroid.getDb().findList(User.class)
    .limit(10) // Records per page
    .offset(10) // Skip first 10 records (for page 2)
    .execute();

Query Specific Fields #

Only fetch username and age columns (reduces data transfer):

List<User> userList = IDroid.getDb().findList(User.class)
    .select("username", "age")
    .execute();

• Always include a no-arg constructor in your entity classes—IDroid uses reflection to create instances, and this is non-negotiable.
• Use @Column(name = "column_name") if you want to map a field to a different column name than the field itself; if omitted, it uses the field name by default.
• Avoid running database operations on the main thread (Android will throw a NetworkOnMainThreadException for long operations). Use Kotlin Coroutines, AsyncTask, or RxJava to offload work to background threads.
• Primary keys should preferably be long (not int) to avoid overflow with large datasets.

内容的提问来源于stack exchange，提问作者user12240680