java - 捕获 SqlJetException 的方法在执行后抛出 SqlJetException

Question

我有一个Database 和一个Control 类。 Database 类 通过提供创建 SQLite 数据库和插入数据等方法，使访问 SQLite 数据库变得更加容易。这些方法可能会抛出 SqlJetException，每个方法都会处理该异常。

Control 类 正在从Database 类 调用这些方法，但提示未捕获SqlJetException。我个人认为 Control 类中的 SqlJetException 处理是糟糕的面向对象设计，因此我想避免这种情况。

我的问题是为什么我的数据库方法会抛出异常，尽管我已经捕获了异常？我该如何解决这个问题？

错误日志

[INFO] --- maven-compiler-plugin:2.5.1:compile (default-compile) @ voc ---
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
[INFO] Compiling 2 source files to /home/toogley/src/voc/target/classes
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] /home/toogley/src/voc/src/main/java/voc/Control.java:[14,23] error: unreported exception SqlJetException; must be caught or declared to be thrown
[ERROR] /home/toogley/src/voc/src/main/java/voc/Control.java:[15,25] error: unreported exception SqlJetException; must be caught or declared to be thrown
[ERROR] /home/toogley/src/voc/src/main/java/voc/Control.java:[16,21] error: unreported exception SqlJetException; must be caught or declared to be thrown
[ERROR] /home/toogley/src/voc/src/main/java/voc/Control.java:[20,21] error: unreported exception SqlJetException; must be caught or declared to be thrown
[INFO] 4 errors 
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------

数据库类:

package voc;

import org.tmatesoft.sqljet.core.*;
import org.tmatesoft.sqljet.core.table.ISqlJetTable;
import org.tmatesoft.sqljet.core.table.SqlJetDb;

import java.io.File;

public class Database {
    private SqlJetDb db;

    public void createNew() throws SqlJetException {
        File dbFile = new File("db.sqlite");
        dbFile.delete();

        try {
            db = SqlJetDb.open(dbFile, true);
            db.getOptions().setAutovacuum(true);
            db.beginTransaction(SqlJetTransactionMode.WRITE);

            db.getOptions().setUserVersion(1);
        } catch (SqlJetException e) {
            e.printStackTrace();
        } finally {
            db.commit();
        }
    }

    public void createTable() throws SqlJetException {
        try {
            db.beginTransaction(SqlJetTransactionMode.WRITE);

            db.createTable("voc");
            db.createIndex("english-term");
            db.createIndex("german-translation");

        } catch (SqlJetException e) {
            e.printStackTrace();
        } finally {
            db.commit();
        }
    }

    public void setData(String englishVoc, String germanTranslation) throws SqlJetException {
        try {
            db.beginTransaction(SqlJetTransactionMode.WRITE);

            ISqlJetTable table = db.getTable("voc");
            table.insert(englishVoc, germanTranslation);

        } catch (SqlJetException e) {
            e.printStackTrace();
        } finally {
            db.commit();
        }
    }

    public String getData(String s) throws SqlJetException {
        String returnVal = "";
        try {
            db.beginTransaction(SqlJetTransactionMode.READ_ONLY);

            ISqlJetTable table = db.getTable("voc");
            returnVal = table.lookup(s).toString();
        } catch (SqlJetException e) {
            e.printStackTrace();
        } finally {
            db.commit();
        }
    return returnVal;
    }

控制类

package voc;

public class Control {

    private Database theDB;

    public Control() {
        theDB = new Database();
    }

    public void fillDB() {
        theDB.createNew(); // <<< SqlJetException
        theDB.createTable(); // <<< SqlJetException
        theDB.setData("mobility", "Ortsunabhängigkeit"); // <<< SqlJetException
    }

    public void receiveData() {
        theDB.getData("test"); // <<< SqlJetException
    }
}

Answer 1

如果您捕获了所有这些，则您的方法抛出 SqlJetException 就不再正确，您应该删除方法签名的该部分。

编译器实际上并不理解这种情况，当你声明你的方法抛出这个和那个检查异常时，编译器不会进一步检查它是否为真。只有相反的情况才会被捕获，当您的代码实际上可能会抛出检查异常，并且既没有捕获也没有在方法签名中声明时，您将从编译器收到错误消息。