我正在尝试从数据库中读取表中的所有记录，并使用这些数据进行一些处理。以下是我使用的代码。
package differences;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;
public class ConformancePercentageChecking {
private final String dbDriver = "com.mysql.jdbc.Driver";
private Connection connection = null;
private final String serverName = "localhost";
private final String mydatabase = "google";
private final String username = "root";//kh hoseinpur
private final String password = "123";
private final String extrainfo = "?useUnicode=true&characterEncoding=UTF-8";
int numberOfInsertedIDs = 0;
public void findConformances() {
try {
try {
Class.forName(dbDriver);//a call to forname("X") causes the class named X to be initialized
String url = "jdbc:mysql://" + serverName + "/" + mydatabase + extrainfo;
if (connection == null) {
connection = (Connection) DriverManager.getConnection(url, username, password);
}
} catch (ClassNotFoundException | SQLException e) {
JOptionPane.showMessageDialog(null, "database");
}
String query1, query2, query3, query4, query5, query6, testSuite, id;
PreparedStatement statement1, statement2, statement3, statement4, statement5, statement6;
query1 = "drop table PresConformance;";
query2 = "drop table PostConformance;";
statement1 = connection.prepareStatement(query1);
statement2 = connection.prepareStatement(query2);
statement1.executeUpdate();
statement2.executeUpdate();
query1 = "CREATE TABLE PresConformance(testSuite Text, conformance numeric(10), depthDifference numeric(10),pathLength numeric(10));";
query2 = "CREATE TABLE PostConformance(testSuite Text, conformance numeric(10), depthDifference numeric(10),pathLength numeric(10));";
query3 = "SELECT * FROM presDifference;";
query4 = "SELECT * FROM presdifference;";
query5 = "insert into PresConformance values(?,?,?,?);";
query6 = "insert into PostConformance values(?,?,?,?);";
statement1 = connection.prepareStatement(query1);
statement2 = connection.prepareStatement(query2);
statement3 = connection.prepareStatement(query3);
statement4 = connection.prepareStatement(query4);
statement5 = connection.prepareStatement(query5);
statement6 = connection.prepareStatement(query6);
Map<String, String> map = new HashMap<>();
statement1.executeUpdate();
statement2.executeUpdate();
ResultSet r1, r2, r3, r4;
r1 = statement3.executeQuery();
System.out.println("***1");
r2 = statement4.executeQuery();
System.out.println("***2");
int idCount = 0, depthDifference = 0, totalNumberOfExecutions = 0, testSuitesCounts = 0, difference = 0, pathLength = 0;
float conformancePercentage = 0, sumOfconformancePercentage = 0;
r3 = r1;
r4 = r2;
while (r1.next()) {
testSuitesCounts = 0;
sumOfconformancePercentage = 0;
testSuite = r1.getString("testSuite");
id = null;
id = map.get(testSuite);
if (id == null) {
idCount++;
map.put(Integer.toString(idCount), testSuite);
r3.absolute(r1.getRow());
r3.previous();
while (r3.next()) {
if (testSuite.equals(r3.getString("testSuite"))) {
System.out.println(testSuite + " equal");
totalNumberOfExecutions = r3.getInt("totalNumberOfExecutions");
difference = r3.getInt("difference");
conformancePercentage = (1 - ((float) difference / totalNumberOfExecutions)) * 100;
if (testSuitesCounts == 0) {
String[] testSuite1, testSuite2, testSuite3;
testSuite1 = testSuite.split("_");
testSuite2 = testSuite1[0].split("/");
testSuite3 = testSuite1[1].split("/");
depthDifference = Math.abs(testSuite2.length - 1) - testSuite3.length;
pathLength = (testSuite2.length - 1) + testSuite3.length;
}
testSuitesCounts++;
sumOfconformancePercentage += conformancePercentage;
}
}
statement5.setString(1, testSuite);
statement5.setFloat(2, (sumOfconformancePercentage / testSuitesCounts));
statement5.setInt(3, depthDifference);
statement5.setInt(4, pathLength);
statement5.executeUpdate();
}
System.out.println(r1.getRow());
}
System.out.println("Pres Finished*****************************************");
idCount = 0;
map = new HashMap<>();
while (r2.next()) {
testSuitesCounts = 0;
sumOfconformancePercentage = 0;
testSuite = r2.getString("testSuite");
id = null;
id = map.get(testSuite);
if (id == null) {
idCount++;
map.put(Integer.toString(idCount), testSuite);
r4.absolute(r2.getRow());
r4.previous();
while (r4.next()) {
if (testSuite.equals(r4.getString("testSuite"))) {
System.out.println(testSuite + " equal");
totalNumberOfExecutions = r4.getInt("totalNumberOfExecutions");
difference = r4.getInt("difference");
conformancePercentage = (1 - ((float) difference / totalNumberOfExecutions)) * 100;
if (testSuitesCounts == 0) {
String[] testSuite1, testSuite2, testSuite3;
testSuite1 = testSuite.split("_");
testSuite2 = testSuite1[0].split("/");
testSuite3 = testSuite1[1].split("/");
depthDifference = Math.abs(testSuite2.length - 1) - testSuite3.length;
pathLength = (testSuite2.length - 1) + testSuite3.length;
}
testSuitesCounts++;
sumOfconformancePercentage += conformancePercentage;
}
}
statement6.setString(1, testSuite);
statement6.setFloat(2, (sumOfconformancePercentage / testSuitesCounts));
statement6.setInt(3, depthDifference);
statement6.setInt(4, pathLength);
statement6.executeUpdate();
}
}
System.out.println("Post Finished*****************************************");
System.out.println("Finished Inserting to DB");
} catch (SQLException ex) {
Logger.getLogger(DifferencesPresPost.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
问题是，对于包含表记录的ResultSet对象r1和r3，它只迭代一次，然后到达ResultSet对象的末尾。
我尝试在每个while循环之前计算两个ResultSet对象中的记录数，并且它正确地打印了recored的数量，但是当它进入这些while循环时，它仅适用于每个ResultSet对象的第一行。 任何人都可以帮我找出这个问题的结果吗？
答案 0 :(得分：-1)
我相信默认情况下你的结果集是TYPE_FORWARD_ONLY。在准备预准备语句时，需要指定TYPE_SCROLL_INSENSITIVE。希望这可以帮助。