Java 打开csv以将结果集导出为字符串类型
我想将sql查询的结果集导出到csv文件。我正在使用opencsv导出到csv文件。我使用下面的代码来实现它Java 打开csv以将结果集导出为字符串类型,java,csv,export-to-csv,opencsv,Java,Csv,Export To Csv,Opencsv,我想将sql查询的结果集导出到csv文件。我正在使用opencsv导出到csv文件。我使用下面的代码来实现它 ResultSet rs = statement.executeQuery(queryString); CSVWriter writer = new CSVWriter(new fileWriter "testFile.csv"), '|',CSVWriter.NO_QUOTE_CHARACTER); writer.writeAll(rs, true); 但我面临的问题是,它会自动导出
ResultSet rs = statement.executeQuery(queryString);
CSVWriter writer = new CSVWriter(new fileWriter "testFile.csv"), '|',CSVWriter.NO_QUOTE_CHARACTER);
writer.writeAll(rs, true);
但我面临的问题是,它会自动导出到来自resultset的数据库列的数据类型
例如,如果我在csv文件的数据类型中看到一个列的数据类型为float,那么我将看到100.00,对于另一个列,我将看到204192800的值为2.041928E+8
但我想将csv文件导出为字符串类型。以DB为单位的值
有人知道如何使用opencsv将resulttype导出为具有字符串数据类型的csv文件吗?非常感谢您的帮助。您可以创建SQl has字符串示例 oracle的示例:
select num||'',to_char(num2) from xxx
或者使用Sql数字格式化程序,结果集响应使用字符串值而不是数字值。您可以创建Sql has字符串示例 oracle的示例:
select num||'',to_char(num2) from xxx
或者使用Sql数字格式化程序,结果集响应使用字符串值而不是数字值。另一种解决方案是,
使用真实结果集(源)创建自定义结果集包装器并调用
此外,您还可以创建自定义ResultSetMetaData包装,以响应ColumnType具有字符串
writer.writeAll(new MyResultSet(rs), true);
//Wrapper class
public class MyResultSet implements Resultset{
public MyResultSet(Resultset source, Map<String, NumberFormat > formatters){
//setting constructor properties and you can read here SQL resultset Metadata to complete formatters
}
//.... you will implement all sql.Resultset methods
//example to implements
public String getString(String columnName){
return formatters.get(columnName).format(source.getInt(columnName));
}
public ResultSetMetaData getMetaData(){
return new MyResultSetMetaData(source);
}
}
}
//
public MyResultSetMetaData implements ResultSetMetaData{
//will implement all ResultSetMetaData methods,
//replace Numeric to String the column Type, then the value has retrieved by getString(column)
public int getColumnType(int columnIndex){
return Types.VARCHAR;
另一个解决办法是,
使用真实结果集(源)创建自定义结果集包装器并调用
此外,您还可以创建自定义ResultSetMetaData包装,以响应ColumnType具有字符串
writer.writeAll(new MyResultSet(rs), true);
//Wrapper class
public class MyResultSet implements Resultset{
public MyResultSet(Resultset source, Map<String, NumberFormat > formatters){
//setting constructor properties and you can read here SQL resultset Metadata to complete formatters
}
//.... you will implement all sql.Resultset methods
//example to implements
public String getString(String columnName){
return formatters.get(columnName).format(source.getInt(columnName));
}
public ResultSetMetaData getMetaData(){
return new MyResultSetMetaData(source);
}
}
}
//
public MyResultSetMetaData implements ResultSetMetaData{
//will implement all ResultSetMetaData methods,
//replace Numeric to String the column Type, then the value has retrieved by getString(column)
public int getColumnType(int columnIndex){
return Types.VARCHAR;
我认为最好的办法是
writer.setResultService(new MyResultSetSevice());
writer.writeAll(rs, true);
并创建一个类
//http://opencsv.sourceforge.net/apidocs/index.html?au/com/bytecode/opencsv/CSVWriter.html
public class MyResultSetSevice implements ResultSetHelper{
public String[] getColumnValues(ResultSet rs)
{
return formattedColumnValues;
}
String[] getColumnValues(ResultSet rs, boolean trim) {
return formattedColumnValues;
}
}
我认为最好的办法是
writer.setResultService(new MyResultSetSevice());
writer.writeAll(rs, true);
并创建一个类
//http://opencsv.sourceforge.net/apidocs/index.html?au/com/bytecode/opencsv/CSVWriter.html
public class MyResultSetSevice implements ResultSetHelper{
public String[] getColumnValues(ResultSet rs)
{
return formattedColumnValues;
}
String[] getColumnValues(ResultSet rs, boolean trim) {
return formattedColumnValues;
}
}
另一种选择是显式地写入每一行。这是一个相当简单的方法,其优点是您可以使用“ApplyQuotesToll”参数让CSVWriter只引用需要引号的值,而不是全部或全无
public static void toCSV(ResultSet rs, OutputStream os)
throws SQLException, IOException {
CSVWriter csvWriter = new CSVWriter(new OutputStreamWriter(os));
ResultSetMetaData metadata = rs.getMetaData();
int columnCount = metadata.getColumnCount();
String[] column = new String[columnCount];
for (int i = 1; i <= columnCount; i++) {
column[i-1] = metadata.getColumnName(i);
}
csvWriter.writeNext(column, false);
while (rs.next()) {
for (int i = 1; i <= columnCount; i++) {
column[i-1] = rs.getString(i);
}
csvWriter.writeNext(column, false);
}
csvWriter.close();
}
publicstaticvoidtocsv(结果集rs、输出流os)
抛出SQLException,IOException{
CSVWriter CSVWriter=新的CSVWriter(新的OutputStreamWriter(os));
ResultSetMetaData元数据=rs.getMetaData();
int columnCount=metadata.getColumnCount();
String[]column=新字符串[columnCount];
对于(int i=1;i另一个选项是显式地写入每一行。这是一个相当简单的方法,其优点是您可以使用“ApplyQuotesToll”参数使CSVWriter仅引用需要引用的值,而不是全部或不引用
public static void toCSV(ResultSet rs, OutputStream os)
throws SQLException, IOException {
CSVWriter csvWriter = new CSVWriter(new OutputStreamWriter(os));
ResultSetMetaData metadata = rs.getMetaData();
int columnCount = metadata.getColumnCount();
String[] column = new String[columnCount];
for (int i = 1; i <= columnCount; i++) {
column[i-1] = metadata.getColumnName(i);
}
csvWriter.writeNext(column, false);
while (rs.next()) {
for (int i = 1; i <= columnCount; i++) {
column[i-1] = rs.getString(i);
}
csvWriter.writeNext(column, false);
}
csvWriter.close();
}
publicstaticvoidtocsv(结果集rs、输出流os)
抛出SQLException,IOException{
CSVWriter CSVWriter=新的CSVWriter(新的OutputStreamWriter(os));
ResultSetMetaData元数据=rs.getMetaData();
int columnCount=metadata.getColumnCount();
String[]column=新字符串[columnCount];
对于(int i=1;i