java：产生小数位数为2的随机概率，使得和为1

public static List<InstSec> setDataSec(List<String> instno) {
		List<InstSec> result = new ArrayList<InstSec>();
		String[] mon ={"2014-01","2014-02","2014-03","2014-04"};
		int[] flag ={1,2,3,4,5};

		List<String> instnosub5 = new ArrayList<String>();
		for(int i=0;i<instno.size();i++){
			if(!instnosub5.contains(instno.get(i).substring(0,5))){
				instnosub5.add(instno.get(i).substring(0,5));
			}
		}

		//对于每个organValue，每个月，都有五个等级，对应flag prop
		for(int i=0;i<instnosub5.size();i++){
			for(int j=0;j<mon.length;j++){
				float[] prop = genProp();//注意：在此处产生随机概率
				for(int k=0;k<flag.length;k++){
					InstSec inst=new InstSec();
					inst.setInst_no_sub5(instnosub5.get(i));
					inst.setSa_tx_m(mon[j]);
					inst.setFlag(flag[k]);
					inst.setProp(prop[k]);
					result.add(inst);
				}
			}
		}
		return result;
	}

	public static float[] genProp(){
		//产生概率随机数，且让和为1
		float[] prop =new float[5];
		int[] randInt =new int[5];
		int sum=0;
		for(int i=0;i<5;i++){
			randInt[i]=1+(int)(Math.random()*10);
			sum+=randInt[i];
		}
		DecimalFormat dF=new DecimalFormat(".00");
		float sumprop=0;
		for(int i=0;i<5;i++){
			prop[i]= Float.parseFloat(dF.format(1.0*randInt[i]/sum));
//			System.out.println("prop is "+prop[i]);
			sumprop+=prop[i];
		}
//		System.out.println("sumprop is "+sumprop);
		sumprop=Float.parseFloat(dF.format(sumprop));
		if(sumprop<1)
			prop[4]+=1-sumprop;
		else
			prop[4]-=sumprop-1;
//		System.out.println("prop[4] is "+prop[4]);
		return prop;
	}

　　注意：向SQL中传参数的下标是从1开始，java的substring方法从0开始