Question

奇怪，我在Eclipse Luna中有一个Java应用程序，在调试它时我试图使用F6它不会“跳过”，而是“步入”。

Answer 1

我试图在Eclipse Luna中构建一个Java应用程序。这是一个数据库应用程序 here

有两个源文件（DB.java）：

`import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DB {

public Connection conn = null;

public DB() {
    try {
        Class.forName("com.mysql.jdbc.Driver");
        String url = "jdbc:mysql://localhost:3306/Crawler";
        conn = DriverManager.getConnection(url, "root", "admin213");
        System.out.println("conn built");
    } catch (SQLException e) {
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
}

public ResultSet runSql(String sql) throws SQLException {
    Statement sta = conn.createStatement();
    return sta.executeQuery(sql);
}

public boolean runSql2(String sql) throws SQLException {
    Statement sta = conn.createStatement();
    return sta.execute(sql);
}

@Override
protected void finalize() throws Throwable {
    if (conn != null || !conn.isClosed()) {
        conn.close();
    }
}
}`

和Main.java：

`import java.io.IOException;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;


public class Main {
    public static DB db = new DB();

    public static void main(String[] args) throws SQLException, IOException {
        db.runSql2("TRUNCATE Record;");
        processPage("http://www.mit.edu");
    }

    public static void processPage(String URL) throws SQLException, IOException{
        //check if the given URL is already in database
        String sql = "select * from Record where URL = '"+URL+"'";
        ResultSet rs = db.runSql(sql);
        if(rs.next()){

        }else{
            //store the URL to database to avoid parsing again
            sql = "INSERT INTO  `Crawler`.`Record` " + "(`URL`) VALUES " + "(?);";
            PreparedStatement stmt = db.conn.prepareStatement(sql,
                Statement.RETURN_GENERATED_KEYS);
            stmt.setString(1, URL);
            stmt.execute();

            //get useful information
            Document doc = Jsoup.connect("http://www.mit.edu/").get();

            if(doc.text().contains("research")){
                System.out.println(URL);
            }

            //get all links and recursively call the processPage method
            Elements questions = doc.select("a[href]");
            for(Element link: questions){
                if(link.attr("href").contains("mit.edu"))
                processPage(link.attr("abs:href"));
            }
        }
    }
}`

我忘了将mysql-connector-java-5.1.16-bin.jar包含在buildpath中。这导致在DB（）中发生的初始化中发生异常初始化代码。至少这是我假设Eclipse的行为烦恼（也许这是一个特征？）并且步骤不能正常工作。

Eclipse Luna F6不会跨越

1 个答案: