将嵌入式数据库打包到jar文件中
柯国安
问题内容：
问题答案：
我在eclipse项目中创建了一个derby嵌入式数据库，它在eclipse上运行良好，但是当将该项目打包到Runnable
jar文件中时，它无法连接数据库。
我已经完成了与此视频类似的操作 http://vinayakgarg.wordpress.com/2012/03/07/packaging-java-
application-with-apache-derby-as-jar-executable-using-
eclipse/
这是我的 Communicate.java
import java.io.File;
import java.security.NoSuchAlgorithmException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class Communicate {
private static final String dbURL = "jdbc:derby:imagesDB;create=true";
private static final String tableName = "imageDB";
private static Connection conn = null;
private static Statement stmt = null;
public void insert(String path, String hash, long FileSize,
String label_name) throws NoSuchAlgorithmException, Exception {
try {
stmt = conn.createStatement();
stmt.execute("insert into " + tableName + " values (\'" + path
+ "\'," + FileSize + ",\'" + hash + "\'" + ",\'"
+ label_name + "\')");
stmt.close();
} catch (SQLException sqlExcept) {
sqlExcept.printStackTrace();
}
}
public void createConnection() {
try {
Class.forName("org.apache.derby.jdbc.EmbeddedDriver").newInstance();
// Get a connection
conn = DriverManager.getConnection(dbURL);
} catch (Exception except) {
except.printStackTrace();
}
}
public void createTable() throws SQLException {
Statement st = conn.createStatement();
st.execute("CREATE TABLE "
+ tableName
+ " (fullPath VARCHAR(512), fileSize INTEGER, md5 VARCHAR(512), label_name VARCHAR(100))");
}
public void indexTable() throws SQLException {
Statement st = conn.createStatement();
st.execute("CREATE INDEX imageDBIndex ON imageDB (fullPath, label_name)");
}
public void deleteTable() throws SQLException {
Statement st = conn.createStatement();
st.execute("drop table " + tableName);
}
public String searchBySizeAndMD(String file_path, long size, String hash)
throws SQLException {
StringBuilder sb = new StringBuilder();
Statement st = conn.createStatement();
ResultSet rs = st
.executeQuery("SELECT fullPath, label_name FROM (SELECT * FROM imageDB im WHERE im.fileSize = "
+ size + " ) as A WHERE A.md5 = " + "\'" + hash + "\'");
while (rs.next()) {
sb.append("Image: (" + rs.getString("fullPath")
+ ") is at label: (" + rs.getString("label_name") + ")\n");
}
return sb.toString();
}
public String searchByImageName(String fileName) throws SQLException {
StringBuilder sb = new StringBuilder();
Statement st = conn.createStatement();
ResultSet rs = st
.executeQuery("SELECT fullPath, label_name FROM imageDB im WHERE im.fullPath like \'%"
+ fileName + "%\'");
while (rs.next()) {
File out_path = new File(rs.getString("fullPath"));
if (!fileName.equals(out_path.getName())) continue;
sb.append("Image: (" + out_path.getPath()
+ ") is at label: (" + rs.getString("label_name") + ")\n");
}
return sb.toString();
}
public void deleteLabel(String label) throws SQLException {
Statement st = conn.createStatement();
st.execute("DELETE FROM " + tableName + " WHERE label_name = \'" + label + "\'");
}
}
这个问题有帮助吗？
问题答案：
数据库应位于运行jar的文件夹中。如果不是，请检查docs如何指定connectionURL。如果将项目导出到可运行的jar文件，请指定不解压缩相关库，而不必将其直接提取到jar或本地lib文件夹中。这些库位于derby.jar并且derbytools.jar应该位于类路径或清单类路径中。使用以下代码测试您的
Communicate 类。
import java.io.File;
import java.security.NoSuchAlgorithmException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class Communicate {
private static final String dbURL = "jdbc:derby:imagesDB;create=true";
private static final String tableName = "imageDB";
private static Connection conn = null;
private static Statement stmt = null;
public void insert(String path, String hash, long FileSize,
String label_name) throws NoSuchAlgorithmException, Exception {
try {
stmt = conn.createStatement();
stmt.execute("insert into " + tableName + " values (\'" + path
+ "\'," + FileSize + ",\'" + hash + "\'" + ",\'"
+ label_name + "\')");
stmt.close();
System.out.println("Inserted into table "+ tableName+ " values (\'" + path
+ "\'," + FileSize + ",\'" + hash + "\'" + ",\'"
+ label_name + "\')");
} catch (SQLException sqlExcept) {
sqlExcept.printStackTrace();
}
}
public void loadDriver() {
try {
Class.forName("org.apache.derby.jdbc.EmbeddedDriver").newInstance();
System.out.println("Loaded the appropriate driver");
} catch (Exception except) {
except.printStackTrace();
}
}
public void createConnection() {
try {
// Get a connection
conn = DriverManager.getConnection(dbURL);
System.out.println("Connected to and created database ");
} catch (Exception except) {
except.printStackTrace();
}
}
public void createTable() throws SQLException {
Statement st = conn.createStatement();
st.execute("CREATE TABLE "
+ tableName
+ " (fullPath VARCHAR(512), fileSize INTEGER, md5 VARCHAR(512), label_name VARCHAR(100))");
System.out.println("Created table "+ tableName);
}
public void indexTable() throws SQLException {
Statement st = conn.createStatement();
st.execute("CREATE INDEX imageDBIndex ON imageDB (fullPath, label_name)");
System.out.println("Created index "+ "imageDBIndex");
}
public void deleteTable() throws SQLException {
Statement st = conn.createStatement();
st.execute("drop table " + tableName);
System.out.println("Deleted table "+ tableName);
}
public String searchBySizeAndMD(String file_path, long size, String hash)
throws SQLException {
StringBuilder sb = new StringBuilder();
Statement st = conn.createStatement();
ResultSet rs = st
.executeQuery("SELECT fullPath, label_name FROM (SELECT * FROM imageDB im WHERE im.fileSize = "
+ size + " ) as A WHERE A.md5 = " + "\'" + hash + "\'");
while (rs.next()) {
sb.append("Image: (" + rs.getString("fullPath")
+ ") is at label: (" + rs.getString("label_name") + ")\n");
}
return sb.toString();
}
public String searchByImageName(String fileName) throws SQLException {
StringBuilder sb = new StringBuilder();
Statement st = conn.createStatement();
ResultSet rs = st
.executeQuery("SELECT fullPath, label_name FROM imageDB im WHERE im.fullPath like \'%"
+ fileName + "%\'");
while (rs.next()) {
File out_path = new File(rs.getString("fullPath"));
if (!fileName.equals(out_path.getName())) continue;
sb.append("Image: (" + out_path.getPath()
+ ") is at label: (" + rs.getString("label_name") + ")\n");
}
return sb.toString();
}
public void deleteLabel(String label) throws SQLException {
Statement st = conn.createStatement();
st.execute("DELETE FROM " + tableName + " WHERE label_name = \'" + label + "\'");
}
public static void main(String[] args)
{
Communicate c = new Communicate();
c.loadDriver();
try {
c.createConnection();
c.createTable();
c.indexTable();
c.insert("/some/path", "12323423", 45656567, "label name");
String s = c.searchBySizeAndMD("/some/path", 45656567, "12323423");
System.out.println("Search result: "+ s);
c.deleteTable();
conn.commit();
System.out.println("Committed the transaction");
//Shutdown embedded database
try
{
// the shutdown=true attribute shuts down Derby
DriverManager.getConnection("jdbc:derby:;shutdown=true");
}
catch (SQLException se)
{
if (( (se.getErrorCode() == 50000)
&& ("XJ015".equals(se.getSQLState()) ))) {
// we got the expected exception
System.out.println("Derby shut down normally");
} else {
System.err.println("Derby did not shut down normally");
System.err.println(" Message: " + se.getMessage());
}
}
} catch (Exception e) {
System.err.println(" Message: " + e.getMessage());
} finally {
// release all open resources to avoid unnecessary memory usage
//Connection
try {
if (conn != null) {
conn.close();
conn = null;
}
} catch (SQLException e) {
System.err.println(" Message: " + e.getMessage());
}
}
System.out.println("Communicate finished");
}
}
这是输出：
Loaded the appropriate driver
Connected to and created database
Created table imageDB
Created index imageDBIndex
Inserted into table imageDB values ('/some/path',45656567,'12323423','label name')
Search result: Image: (/some/path) is at label: (label name)
Deleted table imageDB
Committed the transaction
Derby shut down normally
Communicate finished
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