运用jfreechart开发图表，本实例是XY极坐标图的开发，内附注释，手把手教程，完美解决中文乱码、中文标题‘口口口’！-To use jfreechart to develop a chart, this example is the development of a XY polar diagram, containing notes. Step by step tutorial, the perfect solution to the Chinese garbled, especiall